Influence of the Reprocessing by Plasma Melting and Injection Molding on the Thermomechanical Properties of a Ni-Ti SMA Manufactured by VIM

Abstract

Shape Memory Alloys (SMA) metallic materials that change their mechanical and physical properties with temperature variation and mechanical loading, surprising engineers and researchers. In this way, one can develop thermomechanical actuators capable, for example, of generating force by blocking the shape recovery or change the natural frequency of a mechanical system by blocking resonance. The processing of these SMA are countless, each one with its specific limitation and particularity. This study aims to evaluate the influence of rapid solidification of a Ni-Ti SMA that is originally manufactured by Vacuum Induction Melting (VIM) and reprocessed by Plasma Melting (PM) followed by injection molding into different metal molds (steel, brass, aluminum and copper). The influence of such a processing is analyzed through Differential Scanning Calorimetry (DSC) and Electrical Resistance as a function of Temperature (ERT) to determine the effects on transformation temperatures. The results demonstrate that by using the copper mold one can provide greater uniformity of the material properties. Thus, there is the possibility of obtaining different kinds of SMA mini-actuators by PM injection in a copper mold and that includes different shapes and sizes that can be studied further.

An Innovative Shape Memory Actuator

“…This paper focuses on two main issues in SMAs assessment and selection. The first one is the characterization of the thermo-mechanical behavior of SMA materials [20][21][22] and the other is the actuator application of one-way shape memory effect (SME). The selection of the operative temperature range is a crucial point in SMA selection [23].…”