Synthesis of NiTi based nanocomposites reinforced by HA addition

Abstract

NiTi alloy is well known for its unique properties, such as good ductility at room temperature, good corrosion resistance and also thermal shape memory effects. On the other hand hydroxyapatite has a combination of desirable properties, such as low density and excellent compatibility with the bone which used as ceramic reinforced phases can change the properties and thermal stability of the NiTi alloy. In this study, the NiTi alloy matrix shape memory composite reinforced by hydroxyapatite particles was successfully fabricated using mechanical alloying and powder metallurgical process. The structural evaluation of milled and heat treated powders was studied by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The differential scanning calorimetry was used to measure the phase transformation temperatures. The porosity, Vickers' hardness and corrosion resistance of the TiNi-HA composites were investigated. The results show that the increase of the weight ratio of hydroxyapatite causes increase the porosity and decrease the corrosion resistance. The fabricated NiTi alloy matrix composite possesses lower density and higher Vickers' hardness as the pure NiTi shape memory alloy, yet still exhibiting the shape memory effect.