A STUDY OF RATE-DEPENDENCE AT ELEVATED TEMPERATURE FOR AN Al-Cu-Mg ALLOY  

作　　者：Y.Q.Wu H.J.Shi K.S.Zhang 

机构地区：[1]Key Laboratory of Failure Mechanics, Department of Engineering Mechanics, Tsinghua University,Beijing 100084, China Department of Engineering Mechanics, North-Western Polytechnical University, Xi'an 710072, China,Key Laboratory of Failure Mechanics, Department of Engineering Mechanics, Tsinghua University,Beijing 100084, China,Department of Engineering Mechanics, North-Western Polytechnical University, Xi'an 710072, China

出　　处：《Acta Metallurgica Sinica(English Letters)》2004年第4期618-624,共7页金属学报（英文版）

摘　　要：The hot deformation of an Al-Cu-Mg alloy was studied in the two temperature ranges (room temperature-300℃ and 400℃-480℃). The rate-independent flow curves are typical of elasto-plastic response with significant work hardening followed by strain softening below 300℃. Similar dislocation structures with high density tangled into grain interiors were observed by TEM, which suggests that the process of obstacles arresting mobile dislocations results in this macroscopically rate-independence. At 400-480℃, all rate dependent flow behaviors characterized by a continuous softening after an initial work hardening at a small plastic strain show large tensile elongations. Long dislocation segments around the second phases infer their good mobility to climb across obstacles. Grain boundary morphology observed by TEM suggests that the capacity of the grain boundaries to absorb the dislocations sensitively accounts for the rate-dependent mechanical properties.The hot deformation of an Al-Cu-Mg alloy was studied in the two temperature ranges (room temperature-300℃ and 400℃-480℃). The rate-independent flow curves are typical of elasto-plastic response with significant work hardening followed by strain softening below 300℃. Similar dislocation structures with high density tangled into grain interiors were observed by TEM, which suggests that the process of obstacles arresting mobile dislocations results in this macroscopically rate-independence. At 400-480℃, all rate dependent flow behaviors characterized by a continuous softening after an initial work hardening at a small plastic strain show large tensile elongations. Long dislocation segments around the second phases infer their good mobility to climb across obstacles. Grain boundary morphology observed by TEM suggests that the capacity of the grain boundaries to absorb the dislocations sensitively accounts for the rate-dependent mechanical properties.

关 键 词：rate dependence elevated temperature dislocations grain boundary 

分 类 号：TG13[一般工业技术—材料科学与工程]