The evolution of microstructure and the stress rupture properties of long term thermally exposed GH3535 alloy have been investigated. It was found that M6 C carbides presented in the solid solution heat treated sample...The evolution of microstructure and the stress rupture properties of long term thermally exposed GH3535 alloy have been investigated. It was found that M6 C carbides presented in the solid solution heat treated samples. During long term thermal exposure at 700 C, fine M12 C carbides precipitated preferentially at grain boundaries. These carbides coexisted with the pre-exiting M6 C. The stress rupture life of700 C/1000 h exposed sample under creep testing at 650 C/324 MPa is 93 h. It is much longer than that of the solid solution samples. No noticeable changes could be detected in both the microstructure and stress rupture lives when the samples were exposed for time longer than 1000 h M12 C carbides were found to be beneficial to the creep properties. The cracks initiated at the interface of M6 C carbides and matrix, which led to a lower creep rupture life.展开更多
The thermal resistance of the pressure die cast magnesium alloy AZ91D is yet not investigated sufficiently. Inorder to assess the effect of a thermal exposure on the microstructural stability and the mechanical proper...The thermal resistance of the pressure die cast magnesium alloy AZ91D is yet not investigated sufficiently. Inorder to assess the effect of a thermal exposure on the microstructural stability and the mechanical properties, the alloyAZ91D is subjected to a long-term annealing for 1 000 h at 80 °C, 100 °C, 120 °C, 150 °C, 180 °C and 200 °C. After theannealing, the microstructural appearance of the material is investigated by light and scanning electron microscopy andcompared with the as-cast condition. Furthermore, tensile tests, hardness measurements and fracture toughness tests arecarried out and the measured values are discussed on the basis of the microstructural changes. The results reveal thedistinct correlation between the microstructural changes, especially the precipitation of discontinuous and continuousβ-particles (Mg17 Al12), and the mechanical properties.展开更多
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDA020404040)the National High Technology Research and Development Program of China (Grant No. 2012AA03A511)
文摘The evolution of microstructure and the stress rupture properties of long term thermally exposed GH3535 alloy have been investigated. It was found that M6 C carbides presented in the solid solution heat treated samples. During long term thermal exposure at 700 C, fine M12 C carbides precipitated preferentially at grain boundaries. These carbides coexisted with the pre-exiting M6 C. The stress rupture life of700 C/1000 h exposed sample under creep testing at 650 C/324 MPa is 93 h. It is much longer than that of the solid solution samples. No noticeable changes could be detected in both the microstructure and stress rupture lives when the samples were exposed for time longer than 1000 h M12 C carbides were found to be beneficial to the creep properties. The cracks initiated at the interface of M6 C carbides and matrix, which led to a lower creep rupture life.
文摘The thermal resistance of the pressure die cast magnesium alloy AZ91D is yet not investigated sufficiently. Inorder to assess the effect of a thermal exposure on the microstructural stability and the mechanical properties, the alloyAZ91D is subjected to a long-term annealing for 1 000 h at 80 °C, 100 °C, 120 °C, 150 °C, 180 °C and 200 °C. After theannealing, the microstructural appearance of the material is investigated by light and scanning electron microscopy andcompared with the as-cast condition. Furthermore, tensile tests, hardness measurements and fracture toughness tests arecarried out and the measured values are discussed on the basis of the microstructural changes. The results reveal thedistinct correlation between the microstructural changes, especially the precipitation of discontinuous and continuousβ-particles (Mg17 Al12), and the mechanical properties.
