Papers by Keyword: Microstructure Selection Map

Abstract: Gamma titanium aluminide alloys often solidify peritectically and show a coarse, dendritic microstructure, which can lead to unacceptable mechanical properties in the as-cast condition. In view of the development of improved cast alloys, the dependence of the solidifying microstructure on the aluminum content and other alloying elements was investigated. The formation of the observed solidification microstructures is discussed in comparison with microstructure formation maps calculated by the NCU (nucleation and constitutional undercooling) model developed by Hunziker et al. [1].

Abstract: Phase selection and microstructural morphology change of the Cu47Ti33Zr11Ni6Sn2Si1 alloy were investigated through the droplet emulsion technique(DET). The emulsified Cu47Ti33Zr11Ni6Sn2Sil alloy powders showed several different microstructures depending on the amount of undercooling. The amount of undercooling of the powders was monitored by differential thermal analysis and was matched with the microstructures. The phase transition of Cu47Ti33Zr11Ni6Sn2Sil alloy powders according to the increase of undercooling proceeds by the process Cu4Ti3 +CuTi +Cu2Ti +Cu51Zr14 → Cu4Ti3 + CuTi + Cu2Ti + Cu51Zr14 + CuTi2 → Cu2Ti + Cu51Zr14 + CuTi2 → Cu51Zr14 +CuTi2. Specifically, the morphology and scale of the CuTi2 phase were examined by SEM observation, and area fraction measurement using an image analyzer, transmission electron microscopy studies, and microhardness tests showed that the amorphous phase could be synthesized by DET. A microstructure selection map of Cu47Ti33Zr11Ni6Sn2Sil alloy powders for tailored solidification was also suggested.