Phase Evolution in Laser Rapid Forming of Compositionally Graded Ti–Ni Alloys

A graded binary titanium-nickel alloy with a compositional gradient, from elemental Ti to $Ti–23.2at.%$ Ni, has been successfully deposited using laser rapid forming. A metallurgical study of the phase evolution along the compositional gradient showed that a series of phase evolutions $α→α+β→α+β+Ti2Ni→β/B2+Ti2Ni$ have occurred. Phase formation and microstructure evolution along the compositional gradient was analyzed by Scheil–Gulliver and eutectic growth models. In particular, the morphology of the $β/B2+Ti2Ni$ anomalous and coupled eutectic is discussed in detail.