Pr、Ce复合稀土变质处理对ADC12合金耐磨性能的影响

Effect of Pr and Ce Composite Rare Earth on Wear Resistance of ADC12 Alloy

复合稀土(Pr,Ce)是以三元中间合金的形式加入ADC12合金基体中,制备出不同质量分数(0,0.25%,0.5%和0.75%)的(Pr,Ce)复合稀土变质ADC12合金。利用光学显微镜、扫描电镜以及销-盘式摩擦磨损试验机,对比分析不同质量分数的复合稀土变质ADC12合金的微观组织和摩擦磨损性能。结果表明:当(Pr,Ce)复合稀土含量为0.5%时,组织中粗大的α(Al)相变得较为细小,以等轴晶为主,Si相则由原来的长条状转变为短颗粒状。此时,变质ADC12合金的耐磨性能也是最佳的,其摩损率和摩擦系数分别为0.0517 g/mm和0.3695,与未变质处理的合金相比分别降低了35.94%和6.19%,合金耐磨性能在添加了复合稀土之后得到了极大的提升。ADC12合金基体和0.25%的复合稀土变质ADC12合金主要为剥层磨损,0.5%的复合稀土变质合金主要为磨粒磨损,0.75%的复合稀土变质合金主要为粘着磨损。

The Pr and Ce composite rare earth ADC12 alloys with different mass fractions(0,0.25%,0.5% and 0.75%)were fabricated via adding them into the ADC12 matrix in the form of ternary intermediate alloy.Optical microscope,scanning electron microscope and pin-disk friction and wear testing machine were used to analyze the microstructure and friction and wear properties of the ADC12 alloy with different mass fractions.The results showed that when the content of the Pr and Ce rare earth compound was 0.5%,the coarse α(Al)in the microstructure was transformed into smaller,equiaxed crystals,and the Si phase was transformed from long strip to short granular.At this time,the wear resistance of the modified ADC12 alloy was also the best.Its wear rate and friction coefficient were respectively 0.0517 g/mm and 0.3695,which were reduced by 35.94% and 6.19%,respectively compared with the unmodified alloy.The wear resistance has been greatly improved after the addition of the composite rare earths.The ADC12 alloy matrix and 0.25% of the composite rare earth ADC12 alloy were mainly delamination wear,0.5% of the composite rare earth alloy was mainly abrasive wear,and 0.75% of the composite rare earth alloy was mainly adhesive wear.