超细SiC颗粒对球磨制备纳米晶AZ91镁合金组织及性能的影响

Effect of ultrafine SiC particles on microstructure and property of milled nanocrystalline AZ91 magnesium alloys

摘要

摘要:通过机械球磨制备了SiC颗粒（SiC _p）增强镁基复合材料粉末（AZ91‒ xSiC _p， x=5%、10%、15%，体积分数），实现了镁基体纳米化及亚微米级SiC _p在镁基体中的均匀弥散分布，研究了SiC _p对球磨后粉末微观组织的影响规律。结果表明，SiC _p第二相的引入能够促进机械球磨过程中镁基体晶粒的细化，晶粒细化程度随SiC _p体积分数的增加有所加强，同时SiC _p含量的提高对Al元素在镁基体中的固溶及其自身颗粒的细化起到抑制作用。球磨后AZ91‒ xSiC _p（ x=5%、10%、15%）复合粉末的硬度分别为HV 166、HV 175和HV 185，强化机制为细晶强化、弥散强化、固溶强化和承载强化，计算得到AZ91‒5%SiC _p复合粉末不同强化机制所引起的强化效果占比分别为86.9%、7.4%、1.8%和3.8%。

Abstract:The SiC particle (SiC _p) reinforced magnesium matrix composite powders (AZ91‒ xSiC _p, x=5%, 10%, 15%, volume fraction) were synthesized by mechanical milling. After the mechanical milling, the grain size of the magnesium matrix was refined to nanoscale, and the ultrafine SiC particles were dispersed into the magnesium matrix uniformly. The effect of SiC _pon the microstructure of the milled nanocrystalline AZ91 magnesium alloys was analyzed. In the results, SiC _pcould accelerate the refining of magnesium matrix. Meanwhile, both the dissolving of Al element into the magnesium matrix and the refining of SiC _pare inhibited due to the increasing of SiC _p. The hardness of AZ91‒ xSiC _pcomposites ( x=5%, 10%, 15%) is HV 166, HV 175, and HV 185, respectively. The contribution ratio of grain boundary strengthening, Orowan strengthening, solid solution strengthening, and load-bearing strengthening to the milled AZ91‒ xSiC _pcomposites is about 86.9%, 7.4%, 1.8% and 3.8%, respectively.

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