Stress Corrosion Behavior of Mg-2 mass% Sn Alloy by Equal-Channel Angular Extrusion

Abstract

In this work, the stress corrosion behavior of Mg-2 mass% Sn alloy in simulated body fluid solution was systematically investigated to determine its performance in a physiological environment. The effect of equal-channel angular extrusion (ECAE) on stress corrosion behavior of Mg-2 mass% Sn alloy was investigated using three-point bending test. ECAE process changed both grain size and Mg2Sn second phase distribution. The average grain size under homogenization annealing condition (about 123.61 mu m) was significantly reduced to 34.32 mu m after four ECAE passes. Mg2Sn phase formed more uniformly both in the grains and along the grain boundaries with ECAE process. The average volume fraction of Mg2Sn phase increased with increasing passes. The microstructure became more homogeneous with further ECAE passes. In bent-beam stress corrosion test, the average crack depths of samples underwent ECAE process were significantly lower than that of sample under homogenization annealing condition. This showed that the ECAE process could reduce crack propagation rate. The enhancement of stress corrosion resistance is attributable to uniform second phase distribution and grain refinement via ECAE process.