热处理对AlFeCoCrNiTi_(0.2)高熵合金组织与性能的影响

Effect of Heat Treatment on Microstructure and Properties of AlFeCoCrNiTi_(0.2)High Entropy Alloy

采用真空吸铸制备了AlFeCoCrNiTi_(0.2)高熵合金,并分别在600、800和1100℃进行退火处理。通过扫描电子显微镜(SEM)、能谱分析(EDS)、X射线衍射仪(XRD)、纳米压痕仪、万能力学试验机等对不同热处理温度下的合金微观组织结构及力学性能进行了研究。结果表明:铸态和热处理态的AlFeCoCrNiTi_(0.2)高熵合金均为体心立方结构,热处理后由BCC1析出BCC2相形成双相组织(原生相BCC1+析出相BCC2);600℃热处理时的合金硬度为672 HV、弹性模量655.7 GPa、压入深度283.4 nm,压缩塑性28%,断裂强度达到1.75 GPa。而800和1100℃的合金硬度降低,主要是由于BCC相分解形成双相BCC(BCC1+BCC2)固溶体结构,两相间的明显分离使合金强度降低。

AlFeCoCrNiTi_(0.2)high entropy alloy was prepared by vacuum casting and annealed at 600,800 and 1100℃respectively.The microstructure and mechanical properties of the alloy with different heat treatment temperatures were studied by means of Scanning Electron Microscopy(SEM),energy dispersive analysis(EDS),X-ray diffractometer(XRD),nano-indentation instrument and universal mechanical testing machine.The results show that the as-cast and heat-treated AlFeCoCrNiTi_(0.2)high-entropy alloys are body-centered cubic structures.After heat treatment,BCC1 precipitates BCC2 phase to form a biphase structure(primary phase BCC1+precipitated phase BCC2).At 600℃,the hardness of the alloy is 672 HV,the elastic modulus is 655.7 GPa,the pressing depth is 283.4 nm,the compression plasticity is 28%,and the breaking strength is 1.75 GPa.The hardness of 800℃and 1100℃alloy decreases,mainly due to the decomposition of BCC phase to form a biphase BCC(BCC1+BCC2)solid solution structure,which reduces the strength of the alloy.