Fatigue failure is one of the main failure forms of Al-Si-Cu-Mg aluminum alloys. To feature their mechanical aspect of fatigue behavior, the low-cycle fatigue behavior of permanent mold cast and die-cast AI-Si- Cu-Mg ...Fatigue failure is one of the main failure forms of Al-Si-Cu-Mg aluminum alloys. To feature their mechanical aspect of fatigue behavior, the low-cycle fatigue behavior of permanent mold cast and die-cast AI-Si- Cu-Mg alloys at room temperature was investigated. The experimental results show that both permanent mold cast and die-cast AI-Si-Cu-Mg alloys mainly exhibit cyclic strain hardening. At the same total strain amplitude, the diecast AI-Si-Cu-Mg alloy shows higher cyclic deformation resistance and longer fatigue life than does the permanent mold cast AI-Si-Cu-Mg alloy. The relationship between both elastic and plastic strain amplitudes with reversals to failure shows a monotonic linear behavior, and can be described by the Basquin and Coffin-Manson equations, respectively.展开更多
The microstructure of permanent mold cast zinc alloy ZA27 was examined by SEM and TEM after natural aging for 18 months. It was found that the primary a’ phase, peritectic and eutectic phases all decomposed into the ...The microstructure of permanent mold cast zinc alloy ZA27 was examined by SEM and TEM after natural aging for 18 months. It was found that the primary a’ phase, peritectic and eutectic phases all decomposed into the equilibrium well-formed a+r| lamellae or irregular a+T| structure through cellular reaction. The cell colonies nucleated on the interdendritic eutectic T| layer and grew into the primary dendrites, thus first making the phase in the dendrite edges decompose, and then the a’ phase in the dendrite cores. The products from the a’ phase appeared in regular lamellae rather than irregular particles. In addition, a fine, dense transitional phase a’m containing 27.8 mass% Al, with a fee crystal structure and lattice parameter of about 0.4013nm, formed in lamellae. Copper was preferentially concentrated in Zn-rich n phase and existed in the form of Cu-rich e phase (CuZo,) particles, with hep crystal structure and parameters a=0.274nm, c=0.429nm and c/a=l .567.展开更多
文摘Fatigue failure is one of the main failure forms of Al-Si-Cu-Mg aluminum alloys. To feature their mechanical aspect of fatigue behavior, the low-cycle fatigue behavior of permanent mold cast and die-cast AI-Si- Cu-Mg alloys at room temperature was investigated. The experimental results show that both permanent mold cast and die-cast AI-Si-Cu-Mg alloys mainly exhibit cyclic strain hardening. At the same total strain amplitude, the diecast AI-Si-Cu-Mg alloy shows higher cyclic deformation resistance and longer fatigue life than does the permanent mold cast AI-Si-Cu-Mg alloy. The relationship between both elastic and plastic strain amplitudes with reversals to failure shows a monotonic linear behavior, and can be described by the Basquin and Coffin-Manson equations, respectively.
文摘The microstructure of permanent mold cast zinc alloy ZA27 was examined by SEM and TEM after natural aging for 18 months. It was found that the primary a’ phase, peritectic and eutectic phases all decomposed into the equilibrium well-formed a+r| lamellae or irregular a+T| structure through cellular reaction. The cell colonies nucleated on the interdendritic eutectic T| layer and grew into the primary dendrites, thus first making the phase in the dendrite edges decompose, and then the a’ phase in the dendrite cores. The products from the a’ phase appeared in regular lamellae rather than irregular particles. In addition, a fine, dense transitional phase a’m containing 27.8 mass% Al, with a fee crystal structure and lattice parameter of about 0.4013nm, formed in lamellae. Copper was preferentially concentrated in Zn-rich n phase and existed in the form of Cu-rich e phase (CuZo,) particles, with hep crystal structure and parameters a=0.274nm, c=0.429nm and c/a=l .567.
