MANUFACTURABILITY OF IN-SITU TiC REINFORCED MAGNESIUM METAL MATRIX COMPOSITE

Abstract

The present research is aimed at fabrication of magnesium-based metal matrix composite containing to improve mechanical and wear properties along with enhanced joining and machining characteristics. The RZ5-TiC composites with the different weight percentage of TiC have been fabricated using in-situ self-propagating high-temperature synthesis method to achieve the required aims. To study the formation of TiC reinforcement, its size and distribution, as well as the formation of other phases, optical microscopy (OM), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDS) and X-Ray Diffraction (XRD) techniques are used. The mechanical properties like ultimate tensile strength, hardness, ductility and porosity percentage have been examined. The results revealed that the addition of TiC improved the wear resistance and hardness of the RZ5 matrix with the some compromise of ductility. The intended applications of the experimental composite are in the production of weight and wear sensitive aerospace application components like gearbox housing, gearbox panels, etc. accordingly the abrasive wear characteristics, weld-ability and machinability behavior of the composite have also been studied. The abrasive wear characteristics of the experimental composite are examined using pin-on-disc apparatus designed for such purpose. The experiments are conducted based on the full factorial design of experimental technique. The abrasive wear process has been modeled based on the statistical approach by developing regression equations. In the actual industrial applications of materials, welding is the vital process to fabricated components, assemblies and complete structure. However, joining of metal matrix composites (MMCs) by conventional fusion welding process is very challenging. The irregular distribution, segregation of reinforcements, deleterious reaction as well as weld defects such as porosity, defected fusion zones are the major hindrances. Accordingly, in the current investigation, friction stir welding (FSW), which is one of the solid state joining processes is selected to examine weldability of the composite. Usually, the FSW tools used for the MMCs are exceptionally harder than those used for monolithic materials to minimize the possibility of excessive tool wear due to the abrasive nature of reinforcements. Accordingly, the die steel tool used in the current investigations is further hardened by oxy-acetylene gas flame followed by the water quench. It ii indicates that by applying proper tool geometry and welding parameters FSW joints of RZ5- 10wt%TiC in-situ composite having a joint efficiency of 110% can be successfully achieved. To conduct the machinability experiments, a single pass dry turning operation has been performed on the lathe using uncoated cemented carbide tools. The tests are carried out at various cutting speed, feed rates and depth of cut based on full factorial plan of the experiment. Tool wear mechanism, cutting force (Ft), the surface roughness (Ra) and physical appearance of chips were analyzed as the output responses. It has been observed that the efficient machining of RZ5-TiC composites with uncoated cemented carbide tool is possible at a relative higher cutting speed