Synthesis of Intermetallic Compounds from Elemental Powder Mixture

초록

A direct extrusion of elemental powder mixture was studied as a means to obtain intermetallic compounds based on Ni3Al-B and γ-TiAl economically. Reactive sintering and subsequent plastic deformation during hot extrusion were employed to promote homogeneous alloy formation. The alloying reaction from the multi-component elemental powder mixture invariably produced a fine grain structure , resulting in fully density alloys with good tensile properties. Dispersion hardening of Ni3Al-B alloy with oxides(ZrO2) enhanced the yield strength further at elevated temperature. Thermal compatibility was deemed necessary to choose the proper kind of dispersoid. Microstructure of γ-TiAl was controlled by heat treatment such that a fine duplex structure was obtained, which produced a room temperature tensile elongation close to 4%. Microstructural control such as the lamella volume fraction and the ratio between γ and α2 was crucial to optimizing the mechanical properties.