Controlling the mechanical failures of stir-cast Mg-AZ91D alloy using dicalcium silicate reinforcement

Abstract

The poor load-bearing ability of Mg-AZ91D alloy leads to various mechanical failures like fracture, microcracks, ductile failure, and shear failure. To overcome the aforementioned failures, the present study introduces Ca2SiO4 as an effective reinforcement with the Mg-AZ91D matrix. The Mg-Ca2SiO4 composites were prepared with various weight percentages (2.5%, 5%, and 10%) using the conventional stir casting technique in an inert gas condition. The effect of different Ca2SiO4 /reinforcement particle weight percentages on the mechanical behaviour of Mg-Ca2SiO4 is studied. Various characterization tools like Scanning Electron microscope- Elemental mapping, Optical Microscope, X-ray diffractometer, Vickers hardness tester, Charpy impact tester, and Universal testing machine were employed. The morphology study confirmed the movement of Ca2SiO4 particles into an intergranular region of the Mg-AZ91D matrix, which played a vital role in the grain refinement of Mg-Ca2SiO4 composites. Mg-Ca2SiO4 composite produced a grain size of 84 µm, which is comparatively low than the Mg-AZ91D alloy. The Reinforcement of a higher weight percentage of Ca2SiO4 (10%) has improved the hardness (38.99%), tensile (45.54%), compression strength(31.68 %) and impact strength (31.99%) of Mg-Ca2SiO4 composite. The various strengthening and failure mechanisms associated with the Mg-AZ91D and Mg-Ca2SiO4 composites are further detailed in this study.