形变及退火工艺对Fe47Mn30Co10Cr10B3双相高熵合金组织演变的影响

Effect of Deformation and Annealing Treatment on Microstructure Evolution of FeMnCoCrB Dual-Phase High-Entropy Alloy

利用电子通道衬度显像(ECCI)和EBSD等表征设备研究形变及退火工艺对Fe47Mn30Co10Cr10B3双相高熵合金组织演变的影响。结果表明,随形变量的增加,形变机制分为3个阶段:fcc相内位错滑移主导,相变诱导塑性和位错滑移共同主导,hcp相内位错滑移主导。随退火时间的增加,组织发生部分再结晶到完全再结晶的转变。在晶界处的第二相可有效抑制再结晶晶粒长大,从而获得混晶组织。退火孪晶变体受fcc晶粒取向的影响:<101>取向的晶粒内易形成多孪晶变体,<111>和<100>取向的晶粒内易形成单孪晶变体。退火孪晶变体数量影响单变体hcp相的形态特征:无孪晶变体时有利于块状hcp相形成,单个孪晶变体时有利于条状hcp相形成。fcc晶粒尺寸影响hcp变体数量:大尺寸晶粒有利于多个hcp变体形成,而小尺寸晶粒有利于单个hcp变体形成。

In recent years,non-equiatomic high-entropy alloy(HEA)has been proposed to explore the flexibility of its design rule,avoiding the strength-ductility tradeoff.For further progress,non-equiatomic HEAs doped with interstitial atoms are developed.Boron,an effective dopant in metallurgy,has been used due to the beneficial compositional effects on the interfaces of metallic materials.In this work,the effects of deformation and annealing treatments on the microstructural evolution of Fe47Mn30Co10Cr10B3 dualphase HEAs were investigated via electron channeling contrast imaging(ECCI)and EBSD.The results show that there are three stages in the deformation mechanism with an increase in the deformation degree,which include the dominant dislocation slip in the fcc phase,joint deformation of the transformationinduced plasticity and dislocation slip,and activation of dislocation slip in the hcp phase.With an increase in the annealing holding time,the partial recrystallization transformed to complete recrystallization.Further,particles located in the grain boundary can effectively restrain grain growth,and in turn,exhibit the bimodal grain size.The amount of annealing twinning variants is influenced by the fcc grain orientation:grains with<101>orientation are prone to forming multiple twinning variants,whereas,grains with<111>and<100>orientations are prone to forming a single twinning variant.The amount of annealing twinning variants also affected the morphological characteristics of the single hcp variant;the absence of annealing twinning variant is ascribed to the formation of blocky hcp phases and the single annealing twinning variant is attributed to the formation of laminate hcp phase.Moreover,the number of hcp variants was affected by the fcc grain sizes;large-sized grains facilitated the formation of multiple hcp variants,whereas,small-sized grains facilitated the formation of the single hcp variant.