时效处理对(FeNiCoCr)_(90)Al_5Ti_5高熵合金L1_2型析出相及力学性能的影响

Effect of aging treatment on L12 precipitated phase and mechanical properties of(FeNiCoCr)_(90)Al_(5)Ti_(5) high entropy alloy

析出相形态和相稳定性对于调控合金力学性能至关重要。采用低速球磨+热压烧结法制备(FeNiCoCr)_(90)Al_(5)Ti_(5)高熵合金,研究高温(1150℃)和中温(850℃)时效处理对合金析出相类型、形貌、分布及力学性能的影响。结果表明:所制备合金压缩应变量达47%,屈服强度和极限抗压强度分别为948 MPa和1684 MPa,高强度源于晶内L1_(2)结构纳米析出相的强化作用。850℃时效10 h后L1_(2)析出相长大为尺寸超过10μm的等轴晶粒,且部分转变为薄片状HCP结构η相,导致合金屈服强度和极限抗压强度降低。1150℃时效2 h后晶内纳米L1_(2)析出相完全回溶,导致合金屈服强度和极限抗压强度急剧降低。

The morphology and phase stability of precipitated phases are essential for regulating mechanical properties of alloys.The(FeNiCoCr)_(90)Al_(5)Ti_(5) high entropy alloy was prepared by low-speed ball milling and hot-press sintering method,and the effects of high-temperature(1150℃)and medium-temperature(850℃)aging treatment on the types,morphology,distribution and mechanical properties of precipitated phases in the alloy were investigated.The results show that the compressive strain of the prepared alloy reaches 47%,and the yield strength and ultimate compressive strength are 948 MPa and 1684 MPa,respectively.The high strength is due to the strengthening effect of the L1_(2) structure nano-precipitation phases within the crystal.After aging at 850℃for 10 h,the L1_(2) precipitated phases grow into equiaxed grains with a size exceeding 10μm,and some of them transform into a thin lamellar HCP structureηphases,which leads to the decrease of the yield strength and ultimate compressive strength of the alloy.After aging at 1150℃for 2 h,the intracrystalline L1_(2) nano-precipitated phases completely redissolve,which leads to a drastic decrease in the yield strength and ultimate compressive strength of the alloy.