冷轧和再结晶退火对Ta-2.5W合金组织和力学性能的影响

Effect of cold rolling and recrystallization annealing on microstructure and mechanical properties of Ta-2.5W alloy

采用电子束熔炼法制备了Ta-2.5W合金,研究了18.8%、48.5%和75.8%不同冷轧变形量对Ta-2.5W合金显微组织和力学性能的影响,并研究了退火对冷轧Ta-2.5W合金显微组织、性能及织构的影响。结果表明:随着变形量的增加,合金的晶粒不断压扁拉长,变形量75.8%时已经形成明显的纤维组织,合金的硬度和强度随着变形量的增加不断提高,原因是加工硬化。开始变形时合金组织中形成{111}<110>、{111}<121>织构,随着变形量增加,开始出现{100}<110>织构,{111}<121>织构逐渐消失,当变形量达75.8%时主要为{100}<110>织构,只剩下较少的{111}<110>织构;随着退火温度的升高,合金的纤维状组织开始逐渐消失,出现大量的等轴晶粒,发生了再结晶,晶粒尺寸、分布更为均匀,织构强度逐渐降低;1450℃退火保温1 h后,合金再结晶比例达到95.7%,已基本完成再结晶,此时合金中的织构强度大幅降低,约为冷轧态时的50%;退火后合金的强度降低,但塑性显著增加,有利于其后续变形加工。

Ta-2.5W alloy was prepared by electron beam melting method,and the effect of different cold rolling deformations of 18.8%,48.5% and 75.8% on microstructure and mechanical properties of the Ta-2.5W alloy was studied.The effect of annealing on the microstructure,properties and texture of the cold-rolled Ta-2.5W alloy was also investigated.The results show that as the deformation increases,the grains of the alloy continue to flatten and elongate.Typical rolled fibrous structure is observed in the Ta-2.5W alloy with the deformation of 75.8%.The hardness and strength of the alloy continue to improve with the increase of deformation,due to work hardening.At the beginning of deformation,{111}<110> and {111}<121> textures are formed in the alloy structure.As the deformation increases,{100}<110> textures begin to appear,and {111}<121> textures gradually disappear.When the deformation reaches 75.8%,the main texture is {100}<110>,leaving only a few {111}<110> textures.As the annealing temperature increases,the fibrous structure of the alloy gradually disappears,with a large number of equiaxed grains appearing and recrystallization occurring.The grain size and distribution become more uniform,and the texture strength gradually decreases.After annealing at 1450 ℃ for 1 h,the recrystallization ratio of the alloy reaches 95.7%,and the recrystallization is basically completed.At this time,the texture strength in the alloy significantly decreases,about 50% of that in the cold rolled state.After annealing,the strength of the alloy decreases,but the plasticity significantly increases,which is beneficial for its subsequent deformation processing.