(1. 中車(chē)長(zhǎng)春軌道客車(chē)股份有限公司，長(zhǎng)春 130062；
2. 中國(guó)科學(xué)院 長(zhǎng)春應(yīng)用化學(xué)研究所，長(zhǎng)春 130022)
摘 要: 本文研究了熱處理對(duì)砂型鑄造Mg-4Sm-0.6Zn-0.4Zr合金顯微組織和力學(xué)性能的影響，并運(yùn)用光學(xué)顯微鏡、X射線(xiàn)衍射、掃描電子顯微鏡、透射電子顯微鏡以及力學(xué)實(shí)驗(yàn)設(shè)備對(duì)該合金進(jìn)行了表征與分析。結(jié)果表明：鑄態(tài)合金主要有α-Mg和Mg3Sm組成；固溶處理之后，Mg3Sm相完全溶入到基體且晶粒并未發(fā)生明顯長(zhǎng)大。250 ℃峰時(shí)效合金中主要的析出相為基面γ″沉淀相。峰時(shí)效態(tài)合金展示了最好的力學(xué)性能，其抗拉強(qiáng)度、屈服強(qiáng)度和斷后伸長(zhǎng)率分別為210 MPa、153 MPa和4.0%。根據(jù)峰時(shí)效態(tài)合金的強(qiáng)化機(jī)制的定量分析結(jié)果，發(fā)現(xiàn)峰時(shí)效態(tài)合金主要的強(qiáng)化效果來(lái)自于彌散分布的細(xì)小的γ″的沉淀強(qiáng)化，其對(duì)屈服強(qiáng)度的貢獻(xiàn)為120 MPa，約占總屈服強(qiáng)度的80%。
關(guān)鍵字: Mg-Sm；稀土鎂合金；力學(xué)性能；砂型鑄造
（1. CRRC Changchun Railway Vehicles Co., Ltd., Changchun 130062, China;
2. Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China）
Abstract:In this work, the effects of heat treatment on microstructure and mechanical properties of sand-cast Mg-4Sm-0.6Zn-0.4Zr alloy were investigated through the microstructure analysis by optical microscopy(OM), X-ray diffractometry(XRD), scanning electron microscopy(SEM) and transmission electron microscopy(TEM) and mechanical properties testing. The results indicate that the as-cast alloy is mainly comprised of α-Mg matrix and eutectic Mg3Sm phase. After solution treatment, the coarse second phases are almost dissolved into Mg matrix and the grains do not grow significantly. The dominant precipitates of the alloy peak-aged at 250 ℃ are identified as basal γ″ phase. Also, the peak-aged alloy displays the best mechanical properties with ultimate tensile strength of 210 MPa, yield strength of 153 MPa, and elongation to failure of 4.0%. In addition, the dominant strengthening effect in peak-aged alloy is considered as precipitation strengthening induced by the dispersed fine γ″ precipitate based on the quantitative analysis results of the strengthening mechanism. The contribution of precipitation strengthening to yield strength is 120 MPa, accounting for about 80% of the total yield strength.
Key words: Mg-Sm; rare-earth Mg alloy; mechanical properties; sand casting
