Effect of power on microstructure and mechanical properties of Ti₄₄Al₆Nb_1.0Cr_2.0V_0.15Y_0.1B alloy prepared by cold crucible directional solidification

A newly designed alloy Ti₄₄Al₆Nb_1.0Cr_2.0V_0.15Y_0.1B ingot was prepared by the cold crucible directional solidification (CCDS) technique under a range of input power with the constant drawing speed of 8.33μm/s. Experimental results show that the as-cast microcrack can be eliminated completely after CCDS, and the most desirable microstructure, a high percentage of small angle lamellas microstructure is acquired at input power of 45kW. It also indicates that the interlamellar space gradually decreases with the increasing of power. The measurement of nanoindentation hardness shows that the hardness of B₂ and γ phase in all cast routes is consistent, but in lamella, the hardness increase linearly with the interlamellar space decrease after logarithm. The relationship between the interlamellar space and the nanoindentation hardness was given. The room temperature tensile results confirmed with the desirable directional solidification microstructure, the highest ultimate tensile strength (UTS) value and the elongation are achieved.