Microstructures,tensile properties and serrated flow of Al_xCrMnFeCoNi high entropy alloys

Al_xCrMnFeCoNi高熵合金的显微结构、拉伸性能及锯齿流变形为（英文）

Microstructures and mechanical properties of dual-phase AlxCrMnFeCoNi (x=0.4, 0.5, 0.6, at.%) alloys were investigated. Thermomechanical processing leads to a microstructural evolution from cast dendritic structures to equiaxed ones, consisting of face-centered cubic (fcc) and body-centered cubic (bcc) phases in the two states. The volume fraction of bcc phase increases and the size of fcc grain decreases with increasing Al content, resulting in remarkably improved tensile strength. Specifically, the serrated flow occurring at the medium temperatures varies from type A+B to B+C or C as the testing temperature increases. The average serration amplitude of these Al-containing alloys is larger than that of CoCrFeNiMn alloy due to the enhanced pinning effect. The early small strain produces low-density of dislocation arrays and bowed dislocations in fcc grains while the dislocation climb and shearing mechanism dominate inside bcc grains. The cross-slip and kinks of dislocations are frequently observed and high-density-tangled dislocations lead to dislocation cells after plastic deformation with a high strain.

研究双相AlxCrMnFeCoNi(x=0.4,0.5,0.6,摩尔分数,%)高熵合金的显微结构、拉伸力学性能与锯齿流变形为。经热力学处理后合金的显微组织由铸态树枝晶演化为由fcc和bcc组成的等轴晶。随A1含量增加,bcc相体积分数增大,fcc晶粒尺寸减小,合金强度得到显著提高。在中温区间,随试验温度升高,锯齿流变类型发生A+B→B+C(C)转变。因Al原子对位错的钉扎作用较强,含Al合金的平均锯齿应力振幅明显高于不含Al的CoCrFeNiMn合金。早期的小变形使fcc晶粒产生较低密度位错列和弯曲位错,而bcc晶粒中位错的攀移和剪切机制占主导地位。较大塑性变形后,位错的交滑移和扭折现象频繁发生,而高密度的位错缠结形成位错胞结构。