Effect of severe reduction on mechanical properties during hot rolling of Mg–1.6Gd alloys

Abstract

The mechanical properties of severely hot rolled Mg–1.6Gd (wt.%) alloys, such as hardness, ultimate strength, yield strength and ductility have been studied in the context of biodegradable implant materials. Unidirectional rolling (UR) and cross rolling (CR)were applied to prepare Mg–1.6Gd alloy ingots. In general, the mechanical properties of the alloy greatly improved after hot rolling due to a refinement of the microstructures. The relationship between the microstructure and mechanical properties is discussed in detail. Hot rolled samples were prepared in the temperature range of recrystallization(400–550 °C)with a speed of 10 mm min−1 and a total reduction of 95% at 23.75% per pass, with an aim to characterize mechanical properties of the Mg–1.6Gd alloy such as hardness, ultimate strength yield strength and ductility. Tension and hardness testing were carried out and theVickers hardness values for the hot rolled samples were about 40–50 HV. The Vickers hardness increased with increasing hot rolling temperature. The maximum tensile strength and yield strength observed forUR samples were 197 MPa and 157 MPa, respectively and for CR samples, the values were 164 MPa and 107 MPa, respectively. Further, the maximum elongation for UR samples was 26% and, 17% for CR samples. Samples hot rolled with 95% reduction showed a higher ultimate tensile strength and ultimate yield strength than samples hot rolled with 30% reduction. The maximum elongation also differed between the two rates of reduction, where 95% reduction yielded an elongation of 26%, while a 30% reduction resulted in a maximum of 15%. The mechanical properties reported in this work highlight the benefits of Mg–1.6Gd as material for use in degradable implants.