原位合成多元硼化物对Al0.5CoCrCuFeNiBx高熵合金硬度与耐磨性能的影响

本文研究了Al0.5CoCrCuFeNiBx (x=0-1)的组织、相组成、硬度及耐磨性能。并预测了Al0.5CoCrCuFeNiBx (x=0-1)中简单固溶体形成规律。未添加硼元素的合金具有简单FCC固溶体结构。添加硼元素后，合金由简单FCC固溶体及多元硼化物组成。硼以硼化物形式析出，没有固溶到FCC固溶体中，因而添加硼对FCC固溶体的晶格常数无影响。硼化物的析出使合金的硬度提高，并且硬度随着硼含量的增加而呈线性增加。当硼含量x?0.4时，合多的磨耗阻变化不明显，但当硼含量x?0.6时，合金的磨耗阻抗随着硼含量增加而呈线性增加。 随着硼含量的增加，合金的磨损机制由粘着磨损转变为氧化磨损。合金硬度与耐磨性能的提高是高硬度的粗大硼化物与韧性的FCC固溶体基体共同作用的结果。

Enhanced hardness and wear property by in-situ formation of mul-ti-component borides in Al0.5CoCrCuFeNiBx high-entropy alloys

In this study, the microstructure, phase assemblages, hardness and wear properties of Al0.5CoCrCuFeNiBx (x=0-1) high-entropy alloys were investigated. The parameters representing simple solid-solution formation ability in Al0.5CoCrCuFeNiBx alloys were estimated. Without boron addition, the alloy was composed of simple FCC solid solution structure. With the addition of boron, the alloys were composed of borides and simple FCC solid solution matrix phase. Boron precipitated as borides instead of entering the crystal structure and thus there is no change in the lattice constant of the matrix FCC phase. Borides precipitation significantly hardens the alloy and the hardness showed a strong correlation to the boron content. There was no distinct difference in the wear resistance of the alloys with x?0.4, but the wear resistance showed a strong relation to the boron content in the alloys with x?0.6. With increasing boron content, the wear mechanism changes from delamination wear to oxidative wear. The great enhancement in the hardness and wear resistance is attributed to the combination of the large hard borides and relatively ductile and tough FCC matrix.