论文部分内容阅读
研究了温度和应力对挤压铸造AZ91-Ca合金压缩蠕变行为的影响,并对蠕变机制和微观组织演变进行了分析。研究发现:在测试温度150℃和应力50 MPa条件下,挤压铸造AZ91-Ca合金的最小蠕变速率仅为2.60×10~(-9)s~(-1),100 h后蠕变变形量仅为0.98%;在测试温度200℃和应力100 MPa条件下,最小蠕变速率达到8.93×10~(-7)s~(-1),20 h后蠕变变形量即达到12.71%。随着测试温度的升高和应力的增大,压缩蠕变过程加速,蠕变变形量和最小蠕变速率迅速升高。在测试温度200℃和应力50~100 MPa范围内,其应力指数n≈8.3,而在应力100 MPa和测试温度150~200℃范围内,其激活能Q≈124 k J。压缩蠕变过程中,二次Mg_(17)Al_(12)相不断析出。与高应力相比,高温更能促进二次Mg_(17)Al_(12)相的析出。
The effect of temperature and stress on the compressive creep behavior of squeeze cast AZ91-Ca alloy was studied. The creep mechanism and microstructure evolution were also analyzed. The results show that the minimum creep rate of squeeze cast AZ91-Ca alloy is only 2.60 × 10 -9 s -1 at the test temperature of 150 ℃ and the stress of 50 MPa. After 100 h creep deformation The minimum creep rate reached to 8.93 × 10 ~ (-7) s ~ (-1) at the test temperature of 200 ℃ and the stress of 100 MPa. The creep deformation reached 12.71% after 20 h. With the increase of the test temperature and the increase of the stress, the compressive creep process accelerates, the amount of creep deformation and the minimum creep rate increase rapidly. The stress exponent n≈8.3 at a test temperature of 200 ℃ and a stress of 50 ~ 100 MPa, and an activation energy of Q≈124 kΩ at a stress of 100 MPa and a test temperature of 150 ~ 200 ℃. In the process of compressive creep, the secondary Mg 17 Al 12 phase precipitates continuously. Compared with high stress, high temperature can promote the precipitation of the secondary Mg 17 Al 12 phase.