Xu Yiku, Li Congling, Huang Zhaohao, Chen Yongnan, Zhu Lixia
School of Material Science and Engineering, Chang'an University, Xi'an 710064, China.
CNPC Tubular Goods Research Institute, Xi'an 710077, China.
Entropy (Basel). 2020 Jul 18;22(7):786. doi: 10.3390/e22070786.
A CoCrCuFeNiTi high-entropy alloy was prepared using directional solidification techniques at different withdrawal rates (50 μm/s, 100 μm/s, 500 μm/s). The results showed that the microstructure was dendritic at all withdrawal rates. As the withdrawal rate increased, the dendrite orientation become uniform. Additionally, the accumulation of Cr and Ti elements at the solid/liquid interface caused the formation of dendrites. Through the measurement of the primary dendrite spacing (λ) and the secondary dendrite spacing (λ), it was concluded that the dendrite structure was obviously refined with the increase in the withdrawal rate to 500 μm/s. The maximum compressive strength reached 1449.8 MPa, and the maximum hardness was 520 HV. Moreover, the plastic strain of the alloy without directional solidification was 2.11%, while the plastic strain of directional solidification was 12.57% at 500 μm/s. It has been proved that directional solidification technology can effectively improve the mechanical properties of the CoCrCuFeNiTi high-entropy alloy.
采用定向凝固技术，在不同拉拔速率（50μm/s、100μm/s、500μm/s）下制备了CoCrCuFeNiTi高熵合金。结果表明，在所有拉拔速率下，微观结构均为树枝状。随着拉拔速率的增加，枝晶取向变得均匀。此外，Cr和Ti元素在固/液界面的积累导致了枝晶的形成。通过测量一次枝晶间距（λ）和二次枝晶间距（λ），得出随着拉拔速率增加到500μm/s，枝晶结构明显细化的结论。最大抗压强度达到1449.8MPa，最大硬度为520HV。此外，未进行定向凝固的合金的塑性应变为2.11%，而在500μm/s的拉拔速率下进行定向凝固时，塑性应变为12.57%。已证明定向凝固技术可有效提高CoCrCuFeNiTi高熵合金的力学性能。
