高溫拉伸變形行為
(1. 湖南大學 材料科學與工程學院，長沙 410082;
2. 北京航空材料研究院，北京 100095)
摘 要: 當溫度為300~450 ℃，應變速率為0.001~0.1 s−1時，在WDW-E200拉伸機上采用單向拉伸實驗研究噴射沉積7075Al/SiCp復合材料板材的高溫變形行為；分析板材的變形激活能以及流變應力、變形溫度和應變速率之間的關系。結(jié)果表明：隨著變形溫度升高和應變速率降低，7075Al/SiCp復合材料板材拉伸流變應力減小；其最大拉伸斷裂伸長率由5.03%增加到71.07%；7075Al/SiCp復合材料板材應變速率敏感系數(shù)的最大值僅為0.22，在溫度為623、673和723 K時其變形激活能分別為380.49、323.42和434.56 kJ/mol，均高于鋁的晶格自擴散激活能(142 kJ/mol)。
關鍵字: 鋁基復合材料板材；噴射沉積；高溫拉伸；流變應力；變形激活能
aluminum matrix composite sheet at elevated temperature
（1. College of Materials Science and Engineering, Hunan University, Changsha 410082, China;
2. Beijing Institute of Aeronautical Materials, Beijing 100095, China）
Abstract: The elevated temperature deformation behavior of spray deposited 7075Al/SiCp composite sheet was investigated by uniaxial tensile tests on WDW-E200 at temperature ranging from 300 to 450 ℃ and strain rates between 0.001 and 0.1 s−1. The deformation activity energy and relationship between flow stress and deformation temperature as well as strain rate were analyzed. The results indicate that the tensile flow stress of the composite sheet decreases with increasing deformation temperature and decreasing strain rate，while the maximum elongation to failure increases from 5.03% to 71.07%. The maximum strain rate sensitivity exponent of the 7075Al/SiCp composite sheet is found to be merely 0.22, and the hot activation energy varies at different deformation temperatures, the activation energies at temperatures of 623, 673 and 723 K are 380.49, 323.42 and 434.56 kJ/mol, respectively, which are all larger than the activity energy for lattice self-diffusion in Al (142 kJ/mol).
Key words: Al matrix composite sheet; spray deposited; elevated temperature tensile; flow stress; deformation activation energy
