SYNTHESIS OF MAGNESIUM/B4C SURFACE COMPOSITE BY FRICTION STIR PROCESSING

Abstract

In the new era, cost saving is one of the target of aerospace and automotive industries. To achieve this, there is a requirement of the material having high strength to weight ratio. Magnesium is one of the materials which possess this property. Magnesium-based alloys have enormous potential for cost saving application due to their light weight combine with high specific strength and corrosion resistance, excellent stiffness and damping capacity, as well as good castability and favourable recycling capability. This report is concerned with the fabrication of surface composites. Surface composites are a group of modern engineered materials where the surface of the material is modified by dispersing secondary phase in the form of particles or fibers and the core of the material experience no change in chemical composition and structure. The potential applications of the surface composites can be found in automotive, aerospace, biomedical and power industries. Recently, friction stir processing (FSP) technique has been gaining wide popularity in producing surface composites in solid state itself. Magnesium and its alloys being difficult to process metals also have been successfully processed by FSP to fabricate surface composites. Friction Stir Processing (FSP) is a solid state joining process which uses a non consumable rotating tool inserted into the workpiece for heating and softening the material. This results in material severe plastic deformation resulting in improved mechanical properties and refined grain structure. Most of the research conducted on FSP is confined to aluminium alloys; limited study is done on FSP of magnesium based alloys. In the present work, an attempt has been made to synthesize magnesium based alloy having composition Mg-4Al-3Zn-3Pb-3Sn-0.5misch metal (MM) and Boron Carbide (B4C) micro sized particle surface composite using Friction Stir Processing (FSP). Mechanical properties such as hardness and wear resistance of the FSPed surface composites were evaluated and compared with the properties of base metal. The results indicated that B4C particles were distributed uniformly in the Mg matrix and surface composite exhibited better hardness and wear resistance as compared to base metal.