La对ZL303合金组织与性能的影响

Effects of La on Microstructure and Properties of ZL303 Alloy

利用光学显微镜和力学测试手段,运用统计方法,研究了稀土元素La对ZL303合金组织与力学性能的影响,利用扫描电镜分析了La及其化合物在ZL303合金中的存在状态。结果表明,加入La后,ZL303合金的组织明显细化,Mg2Si相由黑色骨骼状变为短棒状,AlFeMnSi相由灰色网状变为骨骼状。统计分析证明,加入1.0%的La后ZL303合金的抗拉强度有显著提高。Al-5Mg-Si-La合金的抗拉强度和伸长率分别比ZL303合金提高了17%和120%,硬度也有所提高。La及其化合物在ZL303中有两种存在状态:少部分固溶在α-Al基体中,绝大部分偏聚在相界和晶界中。同时,分析了加入La后ZL303合金组织细化和力学性能提高的原因。

Effects of RE element La on microstructure and properties of ZL303 alloy have been investigated by means of optical microscope(OM) and mechanical measurements and orthogonal testing. The distribution of RE element La and its compound phase in the ZL 3030 alloy have been observed by SEM (scanning electron microscope). The results reveal that microstructure of ZL303 can be evidently refined with La addition, in which black skeleton Mg2Si phase is converted into short-rod ones, and gray net-like AlFeMnSi is converted into skeleton ones. Orthogonal testing show that the tensile strength of ZL303 alloy with 1% La addition can be remarkably improved. Compared with that of ZL303 alloy, the tensile strength and elongation of Al-5Mg-Si-La alloy can be increased by 17% and by 120%, respectively, and the hardness can be slightly improved. Majority of La and its compound phase are distributed into the phase interface and grain boundary with minority of them into α-Al phase. In addition, the mechanism of La refining structure and improving mechanical properties of the ZL303 alloy was described.