(1. 西安理工大學 材料科學與工程學院，西安 710048；
2. 西北工業(yè)大學 凝固技術國家重點實驗室，西安 710072)
摘 要: 在電阻爐中采用熔劑保護熔鑄Mg-3Sn-1Y(質量分數，%)合金，并通過Olympus GX71光學顯微鏡(OM)、裝備能譜(EDS)的FEI QUANTA 400型掃描電鏡(SEM)、RigakuD/max-3C型X射線衍射(XRD)、TUKON2100維氏型硬度計和CRY?2P型DTA差熱分析儀等分析合金的鑄態(tài)組織、固溶及時效熱處理對組織和時效硬化的影響。結果表明，Mg-3Sn-1Y合金鑄態(tài)組織由α-Mg枝晶、枝晶間斷續(xù)網狀Mg2Sn相和彌散分布的細小顆粒及短棒狀MgSnY相組成。固溶處理后Mg2Sn相已完全固溶，而具有高溫穩(wěn)定性的MgSnY相依然分布在基體中。加入Y元素可以提高合金的高溫穩(wěn)定性。Mg-3Sn-1Y合金具有典型的時效硬化特征，時效溫度提高，一定程度上有利于時效峰出現；但時效溫度過高，基體組織的長大會降低析出強化作用，延緩峰值硬度的出現。
關鍵字: Mg-3Sn-1Y鎂合金；微觀組織；固溶熱處理；時效硬化
（1. School of Materials Science and Engineering, Xi’an University of Technology, Xi’an 710048, China;
2. State Key Laboratory of Solidification Processing, Northwestern Polytechnical University）
Abstract:A nominal composition of Mg-3Sn-1Y (mass fraction, %) magnesium alloy was prepared by casting with flux protection in electric-resistance furnace. The microstructures as-cast, solution treatment and aging hardening of the Mg-3Sn-1Y alloy by different aging treatments after solution treatment were investigated by an Olympus GX71 optical microscope (OM), an FEI QUANTA 400 scanning electron microscope (SEM) equipped with an energy-dispersive X-ray spectroscop (EDS), a RigakuD/max-3C X-ray diffraction (XRD), a TUKON2100 Vickers hardness tester and a CRY?2P differential thermal analyzer (DTA). The results show that as-cast Mg-3Sn-1Y alloy consists of dendritic α-Mg and intermittent mesh inter-dendrite boundaries Mg2Sn phase, the dispersion tiny particles and fine rod-shaped MgSnY phase. After the solution treatment, the Mg2Sn phase is completely redissolved, and the MgSnY phase with the high temperature stability still distributes in the matrix. The addition of yttrium elements can improve the high temperature stability of Mg-Sn alloy. Mg-3Sn-1Y alloy exhibits obvious aging hardening characteristics. The increase of the aging temperature is advantageous to the occurrence of aging hardening peak to some extent. On the contrary, grain growth of the matrix will decrease the function of separation and strengthening and delay the appearance of aging hardening peak as the ageing temperature is too high.
Key words: Mg-3Sn-1Y magnesium alloy; microstructure; solution heat treatment; aging hardening
