退火处理对CrNiTiMoV高熵合金组织与性能的影响

Effects of Annealing Treatment on Microstructure and Properties of CrNiTiMoV High Entropy Alloy

采用真空电弧熔炼的方法制备CrNiTiMoV高熵合金,分别在600、700、800和900℃下对合金进行2h退火处理。利用X射线衍射仪(XRD)、扫描电镜(SEM)、能谱仪(EDS)、显微硬度计以及电化学工作站对铸态和退火态合金的组织、硬度和耐腐蚀性能进行了研究。结果表明:CrNiTiMoV高熵合金具有典型的树枝晶形貌,晶体结构由简单的BCC相和少量的NiTi相以及富Ti相构成;CrNiTiMoV高熵合金经不同温度退火后未出现新相,随着退火温度升高,富Ti相析出强化,使得合金硬度上升,均大于铸态合金硬度517HV,在800℃/2h退火后,合金硬度达到最大为684HV;在600℃/2h退火后,合金耐腐蚀性能明显提高,但随着退火温度的提高,合金晶粒粗化,富Ti相的析出导致Ti分布不均匀,降低了整体的耐腐蚀性能。

CrNiTiMoV high entropy alloy was prepared by vacuum arc melting and was annealed at 600℃,700℃,800℃and 900℃for 2 h.X-ray diffraction analysis,scanning electron microscopy,energy spectrum analysis,dynamic potential polarization corves and micro Vickers hardness test were conducted to study the effects of annealing treatment on the microstructure,hardness and corrosion resistance of the alloy.The results show that CrNiTiMoV high entropy alloy has typical dendrite morphology,and the crystal structure is composed of simple BCC phase,a small number of NiTi phases and Ti rich phase.No new phase appears after CrNiTiMoV high entropy alloy annealing at different temperatures.As the annealing temperature increases,the rich Ti precipitation enhancement makes the alloy hardness rise harder than the cast alloy hardness of 517 HV.After annealing at 800℃/2 h,the alloy hardness reaches a maximum of 684 HV.After 600℃/2 h annealing,the alloy corrosion resistance is significantly improved,but with the increase of the annealing temperature,the alloy grain coarsening and the precipitation of Ti-rich phase leads to uneven Ti distribution and reduces the overall corrosion resistance.