Microstructure detection of Mg-Zi-Ti-Si amorphous composite coating prepared by SMAT

The Mg-Zn-Ti-Si coating was prepared on Mg alloy through surface mechanical attrition treatment (SMAT) which was simple and low-cost. The microstructure and phase composition of coating were detected through a scanning electron microscope (SEM), an X-ray diffractometer (XRD) and a high resolution transmission electron microscope (HRTEM). The results demonstrated that the layer thickness, which depended on the rotation speed, was 20-80 μm. Although the coating was rough, it was well combined with the matrix. The XRD pattern and HRTEM image analysis demonstrated that the coating contained both amorphous and crystalline phases (Zn, Mg7Zn3 and Si). The process also led to matrix surface strengthening; the mechanisms are solid solution and grain refinement.