Ti对CrCoNi中熵合金微观组织和力学性能的影响

研究了CrCoNiTix中熵合金的金相结构、微观组织和室温力学性能的演化规律。结果表明,当x≤0.1时,合金的相结构为单相面心立方结构(FCC);当0.2≤x≤0.3时,在FCC基体上析出Ti-Ni富集相;当x=0.4时,进一步析出了富Cr相。合金的微观组织由单相时的柱状晶逐渐转变为等轴晶(x=0.4)。少量Ti的固溶几乎不改变合金的屈服强度,而随着第二相的出现,屈服强度显著增加,当x=0.3时达到最大值(1 712.6MPa),而x=0.4时合金的强度和塑性可达到较好的平衡。

Effects of Ti on Microstructure and Mechanical Properties of Cast CrCoNi Medium-entropy Alloy

The effects of Ti on the phase constituent,microstructure and room-temperature mechanical properties of CrCoNi MEA with various Ti ratios which were prepared by arc melting and drop casting were investigated by using X-ray diffractometer and scanning electron microscope,and the compressive properties and hardness were tested.The results show that the crystalline structure is changed from the initial single face-centered cubic(FCC)structure(x≤0.1)to a duplex FCC plus Ni-Ti-rich phase(0.2≤x≤0.3)and then a third Cr-rich phase(x=0.4)with the Ti ratio increase.The as-cast microstructure is transformed from columnar grains to equiaxed grains at x=0.4.The change of yield stress can be ignored with a few addition of Ti,however the yield strength value is increased remarkably with the presence of the second phases.The maximum value of yield strength is achieved of1 712.6 MPa at x=0.3,and a good trade-off between yield stress and ductility is acquired at x=0.4.