L. YAO et al.: EFFECT OF SOLUTION TREATMENT ON THE MICROSTRUCTURE AND MECHANICAL BEHAVIOR ... 655–661 EFFECT OF SOLUTION TREATMENT ON THE MICROSTRUCTURE AND MECHANICAL BEHAVIOR OF THE NICKEL-BASED ALLOY N06625 VPLIV RAZTOPNEGA @ARJENJA NA MIKROSTRUKTURO IN MEHANSKE LASTNOSTI NIKLJEVE ZLITINE VRSTE N06625 Lu Yao 1 , Yugui Li 1,2* , Yaohui Song 1 , Haosong Sun 1 , Yibo Lu 2 , Jiayao Wang 2 1 School of Materials Science and Engineering, Taiyuan University of Science and Technology, Taiyuan, China 2 School of Mechanical Engineering, Taiyuan University of Science and Technology, Taiyuan, China Prejem rokopisa – received: 2023-07-18; sprejem za objavo – accepted for publication: 2023-10-22 doi:10.17222/mit.2023.942 We have studied the effects of different solution temperatures and holding times on the microstructure and room-temperature mechanical properties of the alloy using methods such as electron backscatter diffraction, hardness testing and tensile testing. The results showed that the average grain size increased significantly as the solution temperature increased, and many annealing twins appeared in the grains. The fraction of twin boundaries reached its maximum value at 1080 °C. The hardness, yield strength and tensile strength of the alloy decreased with an increase in the solution temperature, but abnormal yielding occurred at 1160 °C. The elongation after fracture and the area reduction increased with an increase in the solution temperature. The frac- ture morphology of the alloy was irregular, conical, accompanied by a large number of ductile dimples, and the material exhib- ited typical ductile fracture. At the same time, as the solution temperature increased, the number of dimples on the fracture sur- face continued to increase, the depth of the dimples gradually increased, and the distribution became more uniform. Keywords: solution treatment, annealing twin, hardness, tensile behavior Avtorji opisujejo {tudijo vpliva razli~nih temperatur in ~asov zadr`evanja na temperaturi raztopnega `arjenja na mikrostrukturo in mehanske lastnosti pri sobni temperaturi Ni zlitine vrste N06625. Za karakterizacijo so uporabili vrsti~ni elektronski mikroskop z metodo povratno sipanih elektronov, merilnik mikro trdote in natezni preizku{evalni stroj. Rezultati so pokazali, da povpre~na velikost kristalnih zrn mo~no nara{~a z nara{~ajo~o temperaturo raztopnega `arjenja in v mikrostrukturi se pojavi tudi mnogo dvoj~i~nih lamel. Dele` dvoj~i~nih kristalnih mej dose`e svoj maksimum pri 1080 °C. Trdota, meja plasti~nosti in natezna trdnost izbrane zlitine se zmanj{ujejo z nara{~ajo~o temperaturo in ~asom raztopnega `arjenje. Pri temperaturi 1160 °C pa nastopi pojav nenormalnega plasti~nega te~enja. Raztezek in kontrakcija po poru{itvi preizku{ancev nara{~ata z nara{~ajo~o temperaturo raztopnega `arjenje. Prelom preizku{ancev je nepravilne koni~ne oblike in presek preizku{ancev je tipi~no duktilen (`ilav) z velikim {tevilom duktilnih jamic. Isto~asno z nara{~ajo~o temperaturo raste tudi {tevilo in globina duktilnih jamic na povr{ini preloma in njihova porazdelitev postaja enakomernej{a. Klju~ne besede: raztopno `arjenje, dvoj~ki nastali v mikrostrukturi zaradi `arjenja, trdota, natezni preizkus in obna{anje zlitine pod natezno obremenitvijo 1 INTRODUCTION Nickel-based alloys are widely used in various indus- trial processes such as chemical and petrochemical pro- cessing, marine engineering, oil and gas production and transportation, and nuclear reactors. 1,2 Solution heat treatment is applied to heat-resistant alloys after hot working and before service. Its aim is to completely dis- solve the precipitated phase into the matrix after appro- priate hot working and a coarse grain size. 3,4 Coarse grains can reduce the grain boundaries, free energy and lattice mismatch ratio of the alloy. In most cases, coarse-grained alloys are more stable than fine-grained alloys. 5 Grain size plays a decisive role in the tensile properties of metals, and the obstacles to the dislocation movement caused by grain boundaries are very critical. 6 For example, Lan and Zhang 7 studied the effects of the annealing time and temperature on the mechanical prop- erties of Fe-22Mn-0.5C TWIP steel. They showed that in order to obtain products with excellent strength and duc- tility, a specific range of grain sizes should be achieved during an annealing process. Zhang 8 studied the micro- structure characteristics and tensile mechanical proper- ties of gradient-grained nickel-based high-temperature alloys at different temperatures (room temperature, 650 °C, 750 °C) and found that microstructural charac- teristics such as precipitated phases and micro-twins af- fect the tensile deformation behavior of gradient-grained nickel-based high-temperature alloys. In addition, nickel-based alloys, as typical poly- crystalline materials, have extremely important grain boundary characteristics that have a significant impact on physical and mechanical properties. 9 For example, Yuan et al. 10 studied the effect of annealing on Fe-25Mn-3Cr-3Al-0.3C-0.01 N TWIP steel. They found that an increased annealing temperature led to higher densities of 3 grain boundaries and mechanical twins. Studies have shown that an introduction of high-density Materiali in tehnologije / Materials and technology 57 (2023) 6, 655–661 655 UDK 620.186:669.245 ISSN 1580-2949 Original scientific article/Izvirni znanstveni ~lanek MTAEC9, 57(6)655(2023) *Corresponding author's e-mail: liyugui@tyust.edu.cn (Yugui Li) twin boundaries (TBs) in materials such as Cu, 11 Ti, 12 stainless steel 13 and high-entropy alloys has proved to si- multaneously improve strength and ductility. Although ductility can reach a high level, the yield strength of so- lution-strengthened nickel-based alloys is moderate due to the limited solution strengthening effect of solute at- oms. It was reported that in polycrystalline nickel-based high-temperature alloys, coherent TBs are the most vul- nerable part for strain localization and subsequent crack initiation under mechanical loads in different environ- ments. 14 Due to a low stacking-fault energy, polycryst- alline nickel-based high-temperature alloys are prone to produce a high proportion of annealing twins after thermomechanical processing, and more than 50 % of high-angle grain boundaries (HAGBs) in many high- temperature alloys are twins. 15 Therefore, in this research we study the micro- structure characteristics, microhardness and room tem- perature tensile properties of nickel-based alloys at dif- ferent solution temperatures, discussing the effects of microstructure on the mechanical properties of an alloy, and providing a theoretical basis for practical production. 2 EXPERIMENTAL PART The material used in this experiment was forged N06625 alloy, whose main chemical composition (w/%) is shown in Table 1. Specimens were placed in a box-type resistance furnace where solution treatment at (1050, 1080, 1130, 1160 and 1190) °C for 50 min, and at 1130 °C for (10, 30, 50, and 70) min was carried out to study the effect of holding time on the mechanical prop- erties, and then water-quenched to room temperature. The grain size was calculated using the linear intercept method, and the changes between different grain bound- aries were analyzed using electron backscatter diffrac- tion (EBSD). The microhardness of the alloy after solu- tion treatment was tested with a microhardness tester. The test area had to avoid the scratch area. Each sample was tested eight times, and the maximum and minimum values were removed. The average of the remaining six values was taken as the actual microhardness of the sam- ple. Quasi-static tensile tests were carried out on a uni- versal testing machine. Detailed dimensions of the ten- sile specimens are shown in Figure 1. The tensile rate was 1 mm/min. An online computer recorded the load- displacement data. After the test, the tensile properties of the specimens such as yield strength, ultimate tensile strength, elongation of specimens and reduction of area were measured. In addition, scanning electron micros- copy (SEM) was used to observe the fracture surfaces of the alloy tensile specimens. Table 1: Chemical composition of the N06625 nickel-based alloy (wt.%) Ni Cr Mo Cu C Nb Bal. 20.4 8.2 6.1 0.06 3.1 3 RESULTS AND DISCUSSION 3.1 Effect of solution treatment on the microstructure The microstructures of the alloy after solution treat- ment at different temperatures for 50 min are shown in Figure 2. It can be seen that the grain size increases with the increase of solution treatment temperature. In addi- tion, a large number of annealing twins are found in the alloy, which is because for nickel-based alloys with face-centered cubic structure, due to their particular structural composition, the stacking-fault energy of the alloy is relatively low, 16 and a large number of annealing twins are formed during the heat-treatment process. From the microstructure diagram, it can be seen that the twins show different morphologies. Some twins appear at the grain-boundary junctions, some penetrate through the whole grain, and some terminate at the grain interior. The average grain size and twin-boundaries fraction after solution treatment are shown in Table 2. Table 2: Average grain size and twin-boundary fractions of alloy N06625 solution treatment average grain size (mm) twin boundary fractions ( 3, 9, 27, %) 1050 °C-50 min 18.49 47.59 1080 °C-50 min 27.98 75.76 1130 °C-50 min 48.19 50.28 1160 °C-50 min 108.79 40.74 1190 °C-50 min 198.63 39.53 The data in Table 2 shows that at the same holding time, as the solution temperature increases, the average grain size increases continuously. When the solution temperature increases from 1080 °C to 1130 °C, the av- erage grain size increases by about two times, indicating that when the solution temperature is higher than 1080 °C, the driving force for grain growth is greater than the resistance. It is well known that grain growth is charac- terized by grain-boundary migration. From a thermody- namic point of view, a higher solution temperature in- creases the grain-boundary migration rate and the driving force for grain growth, causing some grains to push their boundaries towards other surrounding grains and then achieve mutual engulfment between the grains to form L. YAO et al.: EFFECT OF SOLUTION TREATMENT ON THE MICROSTRUCTURE AND MECHANICAL BEHAVIOR ... 656 Materiali in tehnologije / Materials and technology 57 (2023) 6, 655–661 Figure 1: Detailed dimensions of tensile test specimens (mm) large grains. At the same holding time, grains annealed at higher temperatures will grow to larger sizes due to the higher grain-boundary migration rate. For low-angle grain boundaries (LAGBs), grain-boundary migration is mainly induced by dislocation slip and climb. However, as the dislocation spacing decreases for HAGBs, HAGBs cannot migrate like LAGBs. Usually, atomic jumps be- tween adjacent boundaries are the primary migration mechanism of HAGBs. 9 The annealing twins in the grains should be formed during the grain growth process. When the grains grow through grain-boundary migration, the stacking order of atomic layers at the grain-boundary corners encounters unexpected obstacles. Annealed twins moving towards HAGBs. As the HAGBs grow during movement, if an in- correct layering occurs and a misaligned layer is formed, a complete through-grain annealing twin is formed. At the same time, through analysis, it can be found that the fraction of TBs is controlled at around 40 % as the solu- tion temperature increases, and the maximum proportion of TBs is at 1080 °C. This is because at this temperature, the grain size is small and the grain-boundary area is large, and the obstacles to dislocation movement also in- crease accordingly. Many dislocation accumulations lead to stress concentration and provide the necessary driving force for twins 17 . As the solution temperature increases, the fraction of annealing twins decreases. This is because growing grains collide with each other as annealing pro- gresses, causing the grain-boundary migration rate to de- crease. Therefore, the further development of annealing twins is complex. 9 Figure 2 shows that at 1130 °C, LAGBs are more clustered, with a small amount distrib- uted within the grains. This is because there is an orien- tation difference between two adjacent grains. The larger the orientation difference, the higher the interface energy and the higher the grain-boundary energy. The higher the grain-boundary energy, the more unstable the grain boundary and the greater its migration rate, resulting in a significant increase in the average grain size at this tem- perature. 3.2 Microhardness Figure 3 shows the average hardness values of the al- loy after holding for 50 min at different solution temper- atures. The results show that as the solution temperature increases, the hardness of the alloy shows a gradual downward trend. The hardness of the alloy specimens is affected by factors such as the microstructure, cooling rate, and alloy composition. It has been reported that hardness and grain size have a Hall-Petch relationship, so the hardness of the material decreases as the grain size increases. After solution treatment, the grain size of the alloy specimens gradually increases with the increase in temperature, and even coarsening occurs, so the hardness will gradually decrease. At the same time, under high-temperature conditions, the deformation mecha- nisms of the material increase, and plastic deformation is likely to occur, which manifests as a decrease in strength and a weakening of deformation strengthening, resulting in a hardness lower than that of a low-temperature solu- tion. When the solution temperature is 1050 °C, its hard- ness value is 221.65 Hv. When the temperature is further increased to 1190 °C, the hardness value is the lowest, which is 183.72 Hv. At the same solution-treatment tem- perature, the hardness of the alloy changes little with the extension of time. This phenomenon may be because when holding at this solution temperature, the second phase particles in the alloy continue to dissolve. The holding time is short, and the dissolution rate is not much different, so the hardness change of the alloy tends to be stable. L. YAO et al.: EFFECT OF SOLUTION TREATMENT ON THE MICROSTRUCTURE AND MECHANICAL BEHAVIOR ... Materiali in tehnologije / Materials and technology 57 (2023) 6, 655–661 657 Figure 2: Microstructures of alloy specimens after solution treatment: (a) 1050 °C, (b) 1080 °C, (c) 1130 °C, (d) 1160 °C, (e) 1190 °C, black line: HAGBs, blue line: LAGBs, red line: TBs 3.3 Room-temperature tensile properties The engineering-stress vs. engineering-strain curves of the specimens are shown in Figure 4. It can be seen from Figure 4 that the tensile curve of the alloy is smooth, and it shows different tensile behaviors in differ- ent tensile-test temperature ranges. When the alloy is tensile tested at different solution temperatures, the tensile strength decreases with an in- crease of the solution temperature, and the engineering stress/strain curve has no obvious yield point. During the whole tensile-test process, the flow stress increases first and then decreases. When the solution temperature in- creases from 1050 °C to 1190 °C, both the tensile strength and ductility of the alloy show changes, indicat- ing that compared with the holding time, the mechanical properties of the alloy are more sensitive to the change of grain size with solution temperature. It is primarily found that when the solution temperature is 1080 °C and 1130 °C for 50 min, the tensile curve changes similarly. This is because the fraction of twins is high at this solu- tion temperature, and due to the twin boundary hindering dislocation movement, there will be a large stress con- centration at the interface. 18 When the twin-growth mechanism dominates in plastic deformation, twins will continue to expand. The propagation of twins will be hindered by grain boundaries, leading to severe stress concentration at the grain boundaries and reducing the plastic deformation coordination ability of high-tempera- ture alloys. 19 Under the solution-treatment conditions studied in this paper, the tensile strength ranges from 733 MPa to 833 MPa, and the total elongation ranges from 63.2 % to 80.08 %. When holding at 1130 °C for 10 min to 70 min, the engineering stress-strain curve changes little. Except for holding at 1130 °C for 50 min, with the extension of holding time, the yield strength and tensile strength of the alloy change little. Figure 5 shows the curves of room-temperature ten- sile strength and tensile ductility of the alloy specimens as a function of solution temperature. Tensile strength is a typical indicator of resistance to deformation, indicat- ing the metal’s strength. It can be seen from Figure 5a that when the solution temperature is below 1130 °C, the room-temperature tensile strength and room-temperature L. YAO et al.: EFFECT OF SOLUTION TREATMENT ON THE MICROSTRUCTURE AND MECHANICAL BEHAVIOR ... 658 Materiali in tehnologije / Materials and technology 57 (2023) 6, 655–661 Figure 3: Hardness profile under different solution temperatures and holding times: a) different solution temperatures holding for 50 min, b) dif- ferent holding time at 1130 °C Figure 4: Comparison between engineering stress-strain curves: a) different solution temperatures holding for 50 min, b) different holding time at 1130 °C yield strength gradually decrease with increasing temper- ature. When the solution temperature increases from 1130 °C to 1160 °C, the alloy’s yield strength and tensile strength show a significant upward trend and abnormal yielding occurs. The yield strength reaches 328.48 MPa at 1160 °C, which is the abnormal yield strength. When the solution temperature increases from 1160 °C to 1190 °C, under the action of thermal activation, the yield strength and tensile strength of the alloy show a signifi- cant downward trend. Elongation after fracture is an im- portant parameter reflecting the plasticity of metals. Fig- ure 5b shows the elongation and reduction of the area of the alloy at different solution temperatures. For the duc- tility of the alloy, when the solution temperature in- creases to 1130 ° C, the elongation increases to 72.4 %. However, when the temperature continues to increase to 1160 °C, the change of reduction of area is consistent with that of elongation, both showing a significant down- ward trend. 3.4 Fracture morphology observation Figure 6 shows the nickel-based alloy specimens ob- tained after tensile testing at different solution tempera- tures. The tensile fracture color is dark and dull, the ob- tained specimen diameter is smaller than the original di- ameter, the fracture surface is rough, mainly composed of dimples and tearing edges, and some sharp spikes ap- pear locally. The fracture edge is irregular, cone-shaped, and the fracture shape and morphology of these speci- mens are shown in Figure 6. By observing the fracture microstructure, it can be found that there are many dim- ples on the fracture surface, and there are pits of different depths inside the structure. The pits are caused by local micropore aggregation caused by grain-boundary sliding or dislocation movement 20 , which is the main micro characteristic of metal plastic fracture. Figures 7a and 7b show the fracture morphology and the corresponding pit morphology of the specimen at 1050 °C. The cross-sectional diameter of the fracture de- creases to 2.584 mm. Compared with the original speci- men, the number of dimples on the fracture increases, but the depth of the pits is still shallow. This is because adjacent cracks are difficult to aggregate at relatively low temperatures. 21 Figures 7c and 7d show the fracture morphology at 1080 °C. At this solution temperature, many deeper pits begin to appear, the dimple size becomes more signifi- cant, the fracture surface fluctuates wildly, and there are L. YAO et al.: EFFECT OF SOLUTION TREATMENT ON THE MICROSTRUCTURE AND MECHANICAL BEHAVIOR ... Materiali in tehnologije / Materials and technology 57 (2023) 6, 655–661 659 Figure 5: Comparison of mechanical properties at different solution temperatures: (a) yield strength and tensile strength, (b) elongation after fracture and reduction of area Figure 6: Tensile specimens of alloy N06625 still small dimples with smaller sizes on the fracture edge. At solution temperatures of 1130 °C and 1160 °C, the dimple structure morphology is shown in Figures 7f and 7h. It is worth mentioning that as the degree of de- formation increases, the dimples form undulating and bending stripe morphology, and the stripe pattern is smoothed by deformation, which is generally called the serpentine sliding characteristic. 22 The reason for its for- mation is that after large plastic deformation, shear sepa- ration along the slip plane, mutual restraint, and traction between grains with different orientations, it is impossi- ble to slip only along a particular slip plane but along many intersecting slip planes. Then, the intersection of multiple sliding systems leads to the appearance of this characteristic. 23,24 As the solution temperature increases, at 1190 °C, from the pit morphology shown in Figure 7j, it can be seen that at this time, the number of dimples increases significantly, and there are many large and deep dimples. The dimple size increases significantly, and the fluctua- tion of the fracture surface becomes more evident. The number of tiny dimples on the edge decreases. The re- sults show that as the solution temperature increases, the degree of cross-sectional shrinkage becomes larger and larger. That is the necking degree and the pit size be- comes larger. The more and larger the dimples, the stron- ger the resistance to local instability, so the plasticity is better. 25 4 CONCLUSIONS A series of N06625 alloy samples with different microstructures were prepared by controlling different solid-solution temperatures. The effect of solid-solution treatment on the microstructure evolution and mechani- cal properties of nickel-based N06625 alloy was studied through tissue observation, hardness measurement, and room-temperature tensile mechanical tests. Based on the above results and discussion, the following conclusions can be drawn: (1) As the solution temperature increases, the average grain size increases. There are a large number of anneal- ing twins inside the grains, and the fraction of twin boundaries reaches its maximum at 1080 °C, because the driving force for twin nucleation is optimal at this tem- perature. (2) As the solid-solution temperature increases, the microhardness and tensile strength show a decreasing trend, and the tensile ductility decreases at 1160 °C. This may be due to a further decrease in the twin-boundary fraction. (3) The fracture morphology of the alloy is irregular conical shape with a large number of dimples, which is a typical ductile fracture. As the solution temperature in- creases, the number of pits on the fracture surface in- creases, the depth of pits gradually increases, and the distribution becomes more uniform. L. YAO et al.: EFFECT OF SOLUTION TREATMENT ON THE MICROSTRUCTURE AND MECHANICAL BEHAVIOR ... 660 Materiali in tehnologije / Materials and technology 57 (2023) 6, 655–661 Figure 7: Fracture morphology of the alloy under room-temperature tensile: a), b) 1050 °C, c), d) 1080 °C, e), f) 1130 °C, g), h) 1160 °C, i), j) 1190 °C Acknowledgment This project was supported by the Key Core Technol- ogy and Common Technology Research and Develop- ment Project of the Shanxi Province (20201102017). 5 REFERENCES 1 L. Tan, X. Ren, K. Sridharan, Corrosion behavior of Ni-base alloys for advanced high temperature water-cooled nuclear plants, Corro- sion Science, 50 (2008) 11, 3056–3062, doi:10.1016/j.corsci.2008. 08.024 2 L. Wang, H. Li, Q. Liu, Effect of sodium chloride on the electro- chemical corrosion of Inconel 625 at high temperature and pressure, Journal of Alloys and Compounds, 703 (2017), 523–529, doi:10.1016/j.jallcom.2017.01.320 3 H. Monajati, M. Jahazi, R. Bahrami, The influence of heat treatment conditions on ’ characteristics in Udimet® 720, Materials Science and Engineering: A, 373 (2004) 1–2, 286–293, doi:10.1016/j.msea. 2004.01.027 4 Q. Liu, Z. Liu, G. Gan, Effect of solid solution treatment on microstructure and hardness of Haynes282 heat resistant alloy, Heat Treatment of Metals, 41 (2016) 1, 52–57, doi: 10.13251/j.issn.0254- 6051.2016.01.011 5 Z. L. Tian, S. B. Jiang, Z. Z. Chen, Microstructural evolution and mechanical properties of a new Ni-based heat-resistant alloy during aging at 750°C, Journal of Iron and Steel Research, International, 024 (2017) 005, 513–519, doi:10.1016/S1006-706X(17)30078-X 6 H. Suo, L. Wang, X. Wu, Feasible evolution process of tensile prop- erty dominant effect factor in annealed high purity nickel by a com- bination of in situ tensile technique and EBSD, Materials Today Communications, 35 (2023), doi:10.1016/j.mtcomm.2023.105718 7 P. Lan, J. Zhang, Tensile property and microstructure of Fe-22Mn-0.5C TWIP steel, Materials Science and Engineering: A, 707 (2017), 373–382, doi:10.1016/j.msea.2017.09.061 8 X. Zhang, Y. Chen, L. Cao, Microstructures and tensile properties of a grain-size gradient nickel-based superalloy, Journal of Alloys and Compounds, 960 (2023), doi:10.1016/j.jallcom.2023.170344 9 X.-M. Chen, Y. C. Lin, F. Wu, EBSD study of grain growth behavior and annealing twin evolution after full recrystallization in a nickel-based superalloy, Journal of Alloys and Compounds, 724 (2017), 198–207, doi:10.1016/j.jallcom.2017.07.027 10 X. Yuan, L. Chen, Y. Zhao, Influence of annealing temperature on mechanical properties and microstructures of a high manganese austenitic steel, Journal of Materials Processing Technology, 217 (2015), 278–285, doi:10.1016/j.jmatprotec.2014.11.027 11 Y. Zhang, Y. S. Li, N. R. Tao, High strength and high electrical con- ductivity in bulk nanograined Cu embedded with nanoscale twins, Applied Physics Letters, 91 (2007) 21, 282–285, doi:10.1063/ 1.2816126 12 C. Dai, P. Saidi, Z. Yao, Deformation-free nanotwin formation in zir- conium and titanium, Materials Letters, 247 (2019), 111–114, doi:10.1016/j.matlet.2019.03.029 13 F. K. Yan, G. Z. Liu, N. R. Tao, Strength and ductility of 316L austenitic stainless steel strengthened by nano-scale twin bundles, Acta Materialia, 60 (2012) 3, 1059–1071, doi:10.1016/j.actamat. 2011.11.009 14 C. A. Stein, A. Cerrone, T. Ozturk, Fatigue crack initiation, slip lo- calization and twin boundaries in a nickel-based superalloy, Current Opinion in Solid State and Materials Science, 18 (2014) 4, 244–252, doi:10.1016/j.cossms.2014.06.001 15 N. Bozzolo, N. Souaï, R. E. Logé, Evolution of microstructure and twin density during thermomechanical processing in a - ’ nickel- based superalloy, Acta Materialia, 60 (2012) 13–14, 5056–5066, doi:10.1016/j.actamat.2012.06.028 16 E. G. Astafurova, K. A. Reunova, M. Y. Panchenko, Temperature de- pendence of tensile behavior, deformation mechanisms and fracture in nitrogen-alloyed FeMnCrNiCo(N) Cantor alloys, Journal of Al- loys and Compounds, 925 (2022), doi:10.1016/j.jallcom.2022. 166616 17 Y. Li, H. Fang, X. Zhang, Forming mechanism of growth twins and microstructure evolution on improvement of strength and toughness properties by -eutectoid element in Ti-7Mo-4Al-4Zr-3Nb-2Cr-xFe alloys, Journal of Alloys and Compounds, 947 (2023), doi:10.1016/ j.jallcom.2023.169507 18 Q. U. Pengfei, Y. Wenchao, Y. Quanzhao, The Research and Devel- opment of Micro-Twinning Formation Mechanism in Nickel-based Superalloys, Materials Reports, 33 (2019) 23, 3971–3978, doi:10.11896/cldb.18120160 19 I. S. Kim, B. G. Choi, H. U. Hong, Anomalous deformation behavior and twin formation of Ni-base superalloys at the intermediate tem- peratures, Materials Science and Engineering: A, 528 (2011) 24, 7149–7155, doi:10.1016/j.msea.2011.05.083 20 X. Z. Zhang, T. J. Chen, Y. S. Chen, Effects of solution treatment on microstructure and mechanical properties of powder thixoforming 6061 aluminum alloy, Materials Science and Engineering: A, 662 (2016), 214–226, doi:10.1016/j.msea.2016.03.060 21 Y. Huang, C. Liu, Z. Xiao, Hot tensile deformation and fracture be- haviours of Hastelloy C-276 alloy, Materials Science and Technol- ogy ,34( 2017) 5, 620–627, doi:10.1080/02670836.2017.1407566 22 G. Bai, J. Li, R. Hu, Effect of temperature on tensile behavior of Ni–Cr–W based superalloy, Materials Science and Engineering: A, 528 (2011) 4–5, 1974–1978, doi:10.1016/j.msea.2010.11.053 23 Z. Xiao, Y. Huang, L. Hui, Hot Tensile and Fracture Behavior of 35CrMo Steel at Elevated Temperature and Strain Rate, Metals, 6 (2016) 9, 210, doi:10.3390/met6090210 6(9) 24 Y. C. Lin, J. Deng, Y. Q. Jiang, Hot tensile deformation behaviors and fracture characteristics of a typical Ni-based superalloy, Mate- rials & Design, 55 (2014), 949–957, doi:10.1016/j.matdes.2013. 10.071 25 E. Pu, W. Zheng, Z. Song, Evolution of microstructure and tensile properties during solution treatment of nickel-based UNS N10276 al- loy, Materials Science and Engineering: A, 705 (2017), 335–347, doi:10.1016/j.msea.2017.08.101 L. YAO et al.: EFFECT OF SOLUTION TREATMENT ON THE MICROSTRUCTURE AND MECHANICAL BEHAVIOR ... Materiali in tehnologije / Materials and technology 57 (2023) 6, 655–661 661