Experimental investigation on fracture toughness of Cu-based shape memory alloys with silver addition

Abstract

An attempt is made in the present work to determine the fracture toughness of shape memory alloys by the addition of Ag as a quaternary element. Cu-Al-Mn-Ag shape memory alloys are synthesized by using a bottom pouring type casting machine. Three samples are prepared by varying the Ag concentration by 2%, 4%, and 6% (wt.%) and keeping the Mn content constant (2 wt%). After preparing the samples, they are homogenized in a muffle furnace at 850 °C to achieve the required strength and homogeneity. Single-edged crack specimens are prepared and a three-point bend test was conducted on Universal Testing Machine (UTM) as per ASTM standards. The stress Intensity Factor (KIC) is calculated using an empirical formula. It is observed from the experimental results that Stress Intensity Factor increases with an increase in Ag concentration. Microstructural analysis is conducted using Image Analyzer Microscope. It is observed there is a decrease in grain size with an increase in Ag concentration. According to XRD data, a change in Ag concentration does not significantly alter the size of the crystallites.