真空电弧熔炼轮毂用AlCrFeCuNi-xB高强合金温氧化性能
Oxidation Resistance of AlCrFeCuNi Alloy Modified by B-Doping in Vacuum Arc-Melting
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摘要: 为了提高轮毂用AlCrFeCuNi高强合金在摩擦生热后的抗温氧化能力,本文通过增加B元素的方式,采用真空电弧熔炼法制备了AlCrFeCuNi-xB(x=0、0.05、0.1)高强合金。通过实验测试的方式研究了其微观组织和抗氧化性能。研究结果表明:加入B元素后合金组织中并不会生成脆性B化物。在合金组织内生成了明显的枝晶状结构,并且加入更高比例的B元素后,引起枝晶的细化现象,B化物也随之增加,对基体组织发挥细化效果。合金形成了抛物线特征的恒温氧化曲线,在最初氧化阶段发生了快速氧化,之后逐渐达到相对缓慢状态。经过800℃氧化5 h后,含有更高B的合金表现出更优的耐高温性能。AlCrFeCuNi合金氧化反应得到疏松结构氧化物,加入B元素后都能够显著提高AlCrFeCuNi合金耐氧化性能。加入B能够对Cr在氧化膜中的扩散起到阻碍作用,减少挥发性Cr2O3的产生,有助于促进氧化膜的生成,显著增强合金耐氧化能力。Abstract: The vacuum arc-melting high entropy AlCrFeCuNi alloy,an advanced wheel-hub material for electric railcar,was modified by B-doping to enhance its resistance against high temperature oxidation in friction-heating.The influence of the B-doping on the microstructures and oxidation-resistance was investigated with X-ray diffraction,energy dispersive spectroscopy,and scanning electron microscopy.The results show that the B-doping significantly increased the oxidation resistance instead of forming brittle borides.To be specific,the B-doped AlCrFeCuNi alloy showed the parabolic characteristics in constant temperature oxidation; oxidized at 800℃ for 5 h,0.1%(wt) B-doping decreased the size of dendrite grains,reduced outgassing of volatile Cr2O3,decreased surface porosity,eliminated formation of poriferous and lax structured metal-oxides,and promoted growth of compact surface metal-oxides layer.Consequently,the B-doped AlCrFeCuNi alloy displayed strong high temperature oxidation resistance in friction heating.