The Influence of Ultrasonic Activation on Microstructure, Phase Transformation and Mechanical Properties of Porous Ni-Ti Shape Memory Alloys via Self-Propagating High-Temperature Synthesis.

Abstract

Porous Ni-Ti shape memory alloys (SMAs) have been widely studied in biomedical and engineering applications. Porous Ni-Ti SMAs were obtained via self-propagating high-temperature synthesis (SHS), and their microstructure, phase transformation, and mechanical properties were investigated. This article presents the results of a study of changes in the microstructure, phase transformation, and mechanical properties of porous Ni-Ti SMAs when Ni and Ti metal powders were preliminarily subjected to ultrasonic activation at various periods. It was determined that the porosity of the obtained alloy samples was 62-68 vol%. The microstructure was composed of the main matrix Ni-Ti phase and the accompanying Ti and Ti2-Ni phases. The results show that the hardness 34.1-86.8 HB and elastic modulus 4.2-10.8 GPa increased with an increase in the ultrasonic activation time of the samples. The phase transformation temperature of the Ni-Ti shape memory alloy remained almost unchanged under the influence of ultrasonic treatment.