Powder metallurgical processing of Ni-Ti shape memory alloy

The near net shape production of homogeneous Ni-Ti intermetallic displaying good shape memory behaviour is attractive, particularly for potential biomaterials applications. This study investigates and characterises equiatomic Ni-Ti shape memory ahoy prepared by the compaction and sintering of elemental Ti and Ni powders. Phase development during sintering was determined using X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray analysis, and dimensional integrity of the compacts was monitored during sintering. The shape memory behaviour of the Ni-Ti compacts was assessed using differential scanning calorimetry. Employment of a combined solid state and liquid phase sinter cycle produced homogeneous Ni-Ti intermetallic containing 35% porosity and displaying shape memory transformation enthalpy similar to that of commercially produced wrought Ni-Ti material. (C) 1997 The Institute of Materials.