(1. 太原理工大學(xué) 材料科學(xué)與工程學(xué)院，太原 030024；
2. 太原理工大學(xué) 教育部新材料界面與工程重點(diǎn)實(shí)驗(yàn)室，太原 030024；
3. 太原理工大學(xué) 富士康研發(fā)中心，太原 030024)
摘 要: 采用真空熔化、精煉和無氧化重力鑄造工藝，制備了不同Sr含量的Mg-5Al-0.8Ca-0.2La鎂合金試樣。研究了Sr對該鎂合金的顯微組織、室溫與150~200 ℃溫度區(qū)間內(nèi)力學(xué)性能的影響。結(jié)果表明：基體合金組織除含α-Mg相外，主要由骨骼狀和條狀的Al2Ca相、點(diǎn)狀的Al11La3顆粒相以及少量的β-Mg17Al12相組成；Sr的加入顯著細(xì)化了基體合金的顯微組織，抑制β-Mg17Al12相的析出，并在晶界上析出Mg-Al-Sr三元耐熱相，提高了合金的高溫力學(xué)性能；隨著Sr含量的增加，雖然合金的室溫抗拉強(qiáng)度和伸長率呈下降趨勢，但合金的高溫抗拉強(qiáng)度(σb)和屈服強(qiáng)度(σ0.2)得到明顯提高；當(dāng)Sr含量在0.5%時(shí)，合金的綜合力學(xué)性能最佳。
關(guān)鍵字: 耐熱鎂合金；鍶；Mg-Al-Sr三元相；高溫力學(xué)性能
（1.College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, China;
2. Key Laboratory of Interface Science and Engineering in Advanced Materials, Ministry of Education,
Taiyuan University of Technology, Taiyuan 030024, China;
3. Center of Materials Research and Development of TYUT-Foxcon, Taiyuan University of Technology,
Taiyuan 030024, China）
Abstract: The Mg-5Al-0.8Ca-0.2La-xSr alloys with different Sr contents were melted, refined and non-oxygen-cast under vacuum environment. The effects of addition of Sr on the microstructures and mechanical properties at both room and elevated temperature of 150−200 ℃ for the magnesium alloys were investigated. The results show that the base alloy is composed of Al2Ca and Al11La3 phases, which looks like bones and stripes and small points, respectively, and a small quantity of β-Mg17Al12 phase except α-Mg phase. With addition of Sr, the base alloy is refined remarkably, β-Mg17Al12 phase is restrained, a new heat-resistant phase (Mg-Al-Sr) forms at the grain boundary, which improves the high temperature mechanical properties of alloy. With increasing mass fraction of Sr, the tensile strength and elongation at room temperature decrease. Whereas the tensile strength and yield strength at elevated temperature are improved remarkably. When the mass fraction of Sr is 0.5%, the alloy has the best general mechanical properties.
Key words: heat-resistant magnesium alloy; Sr; Mg-Al-Sr phase; high temperature mechanical properties
