On the Alloying Reaction in Synthesis of NiTi Shape-Memory Alloy in Solid State
Solid-state synthesis of NiTi alloy has gained much interest recently particularly in its porous form for its promising application in medical implant. In this work, powder synthesis by sintering of elemental Ni and Ti for forming equiatomic NiTi alloy was studied. It was found that the alloying reaction in solid state involves complex interaction between the participating elements, their thermodynamics, and the physical constraint of atomic diffusion. A simple model is proposed to explain the phenomenon. Phase characterization was carried out using X-ray diffraction, scanning electron microscope and energy dispersive X-ray. Differential scanning calorimetry was used to examine the transformation behavior of the NiTi alloy. Multiple phases on the Ni-Ti alloy systems were formed and low transformation heat was observed for the synthesized specimen. This paper identifies possible obstacles for forming single-phase NiTi and proposes further work.
KeywordsMigration Furnace Enthalpy Argon Brittle
Authors would like to thank the Universiti Sains Malaysia and the Ministry of Higher Education via Experimental Research Grant Scheme (ERGS) # 203/PMEKANIK/6730014 for partly supporting this work. The input and experimental support from Professor Yinong Liu of the University of Western Australia is also acknowledged.
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