(1. 湖南大學(xué) 汽車車身先進(jìn)設(shè)計(jì)制造國家重點(diǎn)實(shí)驗(yàn)室，長沙 410082；
2. 湖南大學(xué) 材料科學(xué)與工程學(xué)院，長沙 410082)
摘 要: 采用光學(xué)顯微鏡、掃描電子顯微鏡和X射線衍射儀等研究Sr對(duì)AZ91鎂合金組織及力學(xué)性能的影響。結(jié)果表明：添加微量Sr可以細(xì)化并離散AZ91合金的鑄態(tài)共晶組織，在合金晶界處Sr與Al生成多角塊狀或桿狀的Al4Sr高熔點(diǎn)相；當(dāng)Sr含量為0.2%時(shí)，AZ91-0.2Sr合金的綜合力學(xué)性能最優(yōu)，AZ91-Sr合金的時(shí)效進(jìn)程與AZ91合金相比明顯被抑制。由于這些析出相及合金晶界附近Al4Sr高熔點(diǎn)相的強(qiáng)化作用，AZ91-0.2Sr合金經(jīng)T6處理后的室溫和高溫力學(xué)性能皆優(yōu)于原AZ91合金的。
關(guān)鍵字: AZ91鎂合金；鍶；合金化；T6處理；顯微組織；力學(xué)性能
（1. State Key Laboratory of Advanced Design and Manufacture for Vehicle Body, Hunan University, Changsha 410082, China;
2. College of Materials Science and Engineering, Hunan University, Changsha 410082, China）
Abstract:The effect of Sr on microstructures and tensile properties of AZ91 Alloys were investigated by optical microscope, scan electron microscope and X-ray diffraction analyzer. The results show that Sr addition can refine and disperse the net-distributed eutectic structure, high-melting point Al4Sr phase with rob or blocky shaped morphology is observed at the grain boundaries of as-cast AZ91 alloy with Sr additions. AZ91-0.2Sr alloy obtains the best tensile properties comparing with AZ91 and other AZ91-Sr alloys. Comparing with AZ91 alloy, the occurrence of peak hardness of AZ91-0.2Sr alloy is delayed during the aging process. Because of the hard effects of the defined precipitated phase and high-melting point Al4Sr phase, AZ91-0.2Sr alloy after T6-treated also obtains the better tensile properties than that of the former AZ91 alloy at room temperature and 175 .
Key words: AZ91 Mg alloy; Sr; alloying; T6 treatment; microstructure; mechanical properties
