Microstructure and hardness of
binary Cr-Ta alloys
binary Cr-Ta alloys
(State Key Laboratory for Powder Metallurgy,
Central South University, Changsha 410083, China)
Central South University, Changsha 410083, China)
Abstract: The dependences of the microstructure and hardness of the binary Cr-Ta alloys ［Cr-9.0, -9.2, -9.4, -9.6, -9.8, and -13.0 Ta］ ( mole fraction, %) were investigated. When Ta content of the alloy is less than 9.4%, there are primary dendrite grains of a Cr solid-solution phase existing in the matrix of Cr-Cr2Ta eutectic colonies in the alloy. Moreover, the regular polygon grains of the primary Cr2Ta Laves-phase are surrounded by the Cr-Cr2Ta eutectic colony in the hyper-eutectic Cr-9.4%Ta alloys. The scanning electron microphotograph shows that one of the Cr2Ta phase plates of an eutectic colony always connects with the primary Cr2Ta Laves-phase grain in a hyper-eutectic alloy. The eutectic colony size of Cr-Ta alloys decreases with increasing Ta. In addition, the macrohardness of Cr-Ta alloys is influenced by the chemical composition at room temperature. The binary eutectic Cr-Ta alloy presents the lowest hardness on a macrohardness scale.
Key words: binary Cr-Ta alloys; Ta content; Laves-phase