(1. 重慶大學(xué) 材料科學(xué)與工程學(xué)院，重慶 400045；
2. 重慶大學(xué) 國家鎂合金材料工程技術(shù)研究中心，重慶 400030)
摘 要: 通過電子顯微鏡、透射電鏡并結(jié)合塑性變形數(shù)值模擬，觀察鎂合金鑄造缺陷(晶間縮松和縮孔)在變形過程中的形貌變化及缺陷附近應(yīng)力分布，討論塑性變形消除鑄造缺陷的力學(xué)行為，提出鎂合金鑄造缺陷塑性變形彌合過程為：缺陷體積壓縮→界面閉合→界面兩側(cè)基體相切變→界面附近再結(jié)晶→缺陷部分彌合。結(jié)果表明：變形過程中缺陷附近應(yīng)力集中明顯，變形后應(yīng)力集中大大降低，部分鑄造缺陷得以彌合與修復(fù)。
關(guān)鍵字: 鎂合金；鑄造缺陷；塑性變形
plastic deformation
（1. College of Materials Science and Engineering, Chongqing University, Chongqing 400045, China;
2. National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400030, China）
Abstract:The effects of press deformation on the morphologies evolution of Mg alloy casting imperfections (shrinkage porosity and cavity) and the stress distribution around the casting imperfections were observed by electro microscopy, transmission electron microscopy (TEM) and numerical simulation. The mechanical behavior of casting imperfections closing in pressing was investigated. The closing mechanism of press deformation on Mg alloy casting imperfections was proposed, which was volume of casting imperfections shrinking→interfaces closing→shearing deformation of α-Mg matrix grains around interfaces→dynamic recrystallization around interfaces→casting imperfections closing partly. The results show that the stress concentration becomes more evident in pressing and reduces greatly after deformation. At the same time, the casting imperfections are closed and repaired partly.
Key words: magnesium alloy; casting imperfections; plastic deformation
