The transmission electron microscopic morphology of the phases and fatigue crack propagation (FCP) rate of Ti-5Al-2Mo-3Zr alloy were investigated in this study. Microstructure of the alloy consists of α and β phases...The transmission electron microscopic morphology of the phases and fatigue crack propagation (FCP) rate of Ti-5Al-2Mo-3Zr alloy were investigated in this study. Microstructure of the alloy consists of α and β phases after furnace- and air-cooling, and interfacial phase appears at the boundaries between these two phases. After water quenching, the microstructure consists primary of α and h.c.p. martensite α′ which assumes acicular. There are many twins within the α′ plates. No retained β phase exists after quenching from any temperature. During aging, β particles precipitated along the boundaries and inside the martensite plates with Burgers orientation relationship. The fatigue crack propagation rate (low frequency) is not sensitive to the microstructure, tensile strength and rolling direction. Analysis of the fractography shows that main cracks propagated serpentinely and secondary cracks existed everywhere. In high stress intensity range, the resistance of FCP is better than that of Ti-6Al-4V.展开更多
文摘The transmission electron microscopic morphology of the phases and fatigue crack propagation (FCP) rate of Ti-5Al-2Mo-3Zr alloy were investigated in this study. Microstructure of the alloy consists of α and β phases after furnace- and air-cooling, and interfacial phase appears at the boundaries between these two phases. After water quenching, the microstructure consists primary of α and h.c.p. martensite α′ which assumes acicular. There are many twins within the α′ plates. No retained β phase exists after quenching from any temperature. During aging, β particles precipitated along the boundaries and inside the martensite plates with Burgers orientation relationship. The fatigue crack propagation rate (low frequency) is not sensitive to the microstructure, tensile strength and rolling direction. Analysis of the fractography shows that main cracks propagated serpentinely and secondary cracks existed everywhere. In high stress intensity range, the resistance of FCP is better than that of Ti-6Al-4V.
