Effect of mechanical milling on Ni–TiH 2 powder alloy filler metal for brazing TiAl intermetallic alloy: The microstructure and joint's properties

Abstract

A TiH 2–50 wt.% Ni powder alloy was mechanically milled in an argon gas atmosphere using milling times up to 480 min. A TiAl intermetallic alloy was joined by vacuum furnace brazing using the TiH 2–50 wt.% Ni powder alloy as the filler metal. The effect of mechanical milling on the microstructure and shear strength of the brazed joints was investigated. The results showed that the grains of TiH 2–50 wt.% Ni powder alloy were refined and the fusion temperature decreased after milling. A sound brazing seam was obtained when the sample was brazed at 1140 °C for 15 min using filler metal powder milled for 120 min. The interfacial zones of the specimens brazed with the milled filler powder were thinner and the shear strength of the joint was increased compared to specimens brazed with non-milled filler powder. A sample brazed at 1180 °C for 15 min using TiH 2–50 wt.% Ni powder alloy milled for 120 min exhibited the highest shear strength at both room and elevated temperatures.