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利用单辊旋转甩带法制备快速凝固过共晶Al-30Si合金条带,对其进行不同温度下时效4 h和550℃下保温不同时间的时效处理,测定其硬度及耐磨性,采用扫描电镜(SEM)、透射电镜(TEM)及XRD技术对试验合金的微观组织进行表征,研究快速凝固合金时效处理后组织演变及性能。结果表明,快速凝固Al-30Si合金形成了微小初晶Si+纳米级颗粒状共晶硅弥散分布在α(Al)过饱和固溶体基体的复合组织;时效处理过程中,过饱和固溶的Si元素逐渐脱溶析出,以球状或依附于粒状共晶硅而析出生长;时效初期或时效温度较低时,初生硅发生缩颈、熔断、钝化,并逐渐粒化;随时效温度升高,硅相受扩散控制逐渐粗化长大,时效后期或时效温度达到550℃时,硅相逐渐以颗粒搭接和棱角小面特征长大,形态恶化。时效合金组织中硅相体积分数计算结果与定量金相测定结果基本一致。时效合金的显微硬度和耐磨性随时效温度的升高逐渐降低,室温润滑条件下的磨损机制主要为磨粒磨损。
The rapid solidification hypereutectic Al-30Si alloy strip was prepared by a single roll rotation rejection method. The aging of the Al-30Si alloy strip was carried out under different temperatures for 4 h and 550 ℃ for different time. The hardness and wear resistance of the Al-30Si alloy strip were measured by scanning The microstructure of the alloy was characterized by SEM, TEM and XRD. The microstructure and properties of the alloy after rapid aging were investigated. The results show that the microstructure of microstructured Al-30Si alloy is dispersed in α (Al) supersaturated solid solution matrix. During the aging treatment, the supersaturated solution of Si gradually When the initial aging time or aging temperature is low, primary silicon necking, melting, passivation, and gradually grained; with the aging temperature increases, the silicon phase Gradually roughened by diffusion control and growth, late aging or aging temperature reaches 550 ℃, the silicon phase gradually with the characteristics of particle lap and angular facets grew up, morphological deterioration. The results of the calculation of the volume fraction of silicon phase in the aged alloy are basically the same as those of the quantitative metallography. The microhardness and wear resistance of aging alloys gradually decrease with the increase of aging temperature. The wear mechanism of the aging alloy is abrasive wear mainly.