退火温度对(Fe_(50)Mn_(30)Co_(10)Cr_(10))_(97)Al_(3)高熵合金再结晶行为及力学性能的影响

Effect of Annealing Temperatures on Recrystallization Behavior and Mechanical Properties of(Fe_(50)Mn_(30)Co_(10)Cr_(10))_(97)Al_(3) High-Entropy Alloy

以双相亚稳Fe_(50)Mn_(30)Co_(10)Cr_(10)高熵合金为基体,通过添加Al元素,制备了(Fe_(50)Mn_(30)Co_(10)Cr_(10))_(97)Al_(3)高熵合金。对其进行轧制及退火处理,研究了退火温度对合金再结晶行为、退火孪晶演变及力学性能的影响。结果表明,随着退火温度的升高,合金组织分别发生了部分再结晶、完全再结晶和晶粒长大现象。由于高熵合金具有严重的晶格畸变效应及迟滞扩散效应,使得合金在退火后表现出较高的再结晶温度(0.59Tm)和抗晶粒粗化温度(700℃)。600~700℃退火态合金中形成大量退火孪晶,随着退火温度的进一步升高(800~900℃),由于晶界/孪晶界的迁移,退火孪晶界密度显著降低。拉伸试验结果表明,700℃退火态合金表现出良好的综合力学性能,抗拉强度为730 MPa,均匀延伸率为50.5%。同一退火温度下,单个晶粒中退火孪晶变体的数量与其晶粒尺寸有关,尺寸较小的晶粒中易形成单孪晶变体,尺寸较大的晶粒中易形成多孪晶变体。

The(Fe_(50)Mn_(30)Co_(10)Cr_(10))_(97)Al_(3) high-entropy alloy(HEA)was designed by adding Al element into the two-phase metastable Fe_(50)Mn_(30)Co_(10)Cr_(10) HEA.Then,the HEA was treated by rolling and annealing,and the effects of annealing temperature on recrystallization behavior,annealing twin evolution,and the mechanical properties of the alloy were studied.Results show that with increasing the annealing temperature,partial recrystallization,full recrystallization,and grain growth all occur in the alloy.After annealing,HEA exhibits the high recrystallization temperature(0.59Tm)and high grain coarsening temperature(700℃)due to the severe lattice distortion effect and hysteresis diffusion effect of HEA.A Large number of annealing twins are formed in the alloy annealed at 600~700℃.With further increasing the annealing temperature(800~900℃),the content of annealing twins is decreased significantly due to the migration of grain boundaries or twin boundaries.Uniaxial tension results show that the alloy annealed at 700℃has good comprehensive mechanical properties:the tensile strength of 730 MPa and uniform elongation of 50.5%.At the same annealing temperature,the number of annealing twin variants in a single grain is related to the grain size:it is easy to form single annealing twin variant in the small-sized grains and multiple annealing twin variants are easily formed in the large-sized grains.