Characterization of Ni-Ti-Ag Shape Memory Alloy

Abstract

In this paper, specimens of Ni-Ti shape memory alloy incorporating different percentages of Ag nanoparticles are constructed and three of its properties are studied which are density, porosity, and electrical conductivity. The specimens are constructed using powder technology. The construction process involved three main steps; mixing, compacting, and sintering. Before conducting the tests necessary to reveal the alloy properties mentioned above which represent the focus of this work, the constructed ternary Ni-Ti-Ag alloy specimens were first tested to check some of its characteristics and prove that the constructed alloy is a shape memory alloy. These tests included the Differential Scanning Calorimeter (DSC) test, the X-Ray Diffraction (XRD) test, the Scanning Electro-Microscopy (SEM) test, and the Shape Memory Effect (SME) test. The results of these tests reflected the homogeneous distribution of the Ag nanoparticles in the Ni-Ti matrix and indicated the formation of the austenite (Ti2Ni) and martensitie (Ti 002) phases, and that the alloy has a very good SME (89.9% for the 10 wt.% percentage of Ag nanoparticles). Next to this step, porosity test and electrical resistance test were carried out. The results and related calculations for these tests showed that increasing the weight percentage of Ag nanoparticles decreases the porosity and increases the density as well as the electrical conductivity.