二元Mg-Al合金铸态及ECAP态组织与性能研究

Microstructure and Mechanical Properties of the as-Cast and ECAPed Mg-Al Binary Alloy

研究了不同Al含量镁铝二元合金铸态及等通道挤压(ECAP)态组织特征和性能。结果表明:铸态Mg-Al二元合金在含Al(10%～25%,质量分数,下同)范围内,随Al含量增加,α-Mg初晶体积分数逐渐减少,形态由不规则的团絮状变为蔷薇花状,直至小块状;共晶组织体积分数剧增,硬脆相β-Mg17Al12呈网状连续分布,α和β两相以共生生长方式成为片层状共晶组织;ECAP能明显破坏硬脆相β-Mg17Al12网状连续分布,细化共晶组织和初晶α,并能使初晶α中析出弥散细小的β,起到弥散强化作用,使不同Al含量的Mg-Al二元合金不仅抗拉强度得到显著提高,而且塑性获得极大改善,尤其是Mg-15Al合金,ECAP后抗拉强度σb从150MPa提高到269.3MPa,延伸率δ由0.05%提高到7.4%。

Mierostructure and Mechanical properties of the as-cast and equal channel angular pressed （ECAPed） Mg-Al binary alloys with different Al content （10 wt%-25 wt%） were investigated. The results show that, with Al content increasing, primary phase α-Mg in as-cast Mg-Al binary alloy decreases, while eutectic microstructure severely increases. The morphologies of primary phase change from irregular crumby structure, through rocaceous structure, to small blocky structure, while brittle β-Mg17Al12 phase exhibits network-like and α, β eutectic phase display regular lamellar. ECAP can obviously break network of β phase, refine the primary phase α-Mg and eutectic phase and also promote fine β to precipitate from primary phase α-Mg. After ECAP, both tensile strength and elongation of the Mg-Al binary alloys are greatly improved. Especially in the alloy with Al content of 15%, the tensile strength is improved from 150 MPa to 269.3 MPa and its elongation from 0.05% to 7.4%.