A COMPARATIVE STUDY ON EX-SITU & IN-SITU FORMED METAL MATRIX COMPOSITES B. Gobalakrishnan, C. Rajaravi, Gobikrishnan Udhayakumar, P.R. Lakshminarayanan Archives of Metallurgy and Materials, 2023 An attempt has been made to synthesize the aluminium based ex-situ (Al-SiC) and in-situ (Al-TiB2) formed metal matrix composites with varying weight percentage of reinforcement contents such as 4wt.%, 6wt.% and 8wt.%. Synthesized composites were subjected to a cold extrusion process followed by heat treatment according to the ASTM B 918-01 standards. The mechanical properties of in-situ composites were evaluated as per the ASTM guidelines and compared with ex-situ formed composites and base metal properties. Superior properties were noticed in the in-situ formed composites and the mechanical properties such as yield strength, Ultimate tensile strength (UTS) and Hardness for both ex-situ and in-situ composites were found to increase with increasing the reinforcement addition. Cold extruded Al-8 wt.% SiC composite properties such as hardness, yield strength and UTS are 87 RB, 152 MPa, 216 MPa respectively. Whereas, for Al-8 wt.% TiB2 composite, the corresponding properties are 94 RB, 192 MPa, 293 MPa. The morphology of the composites is analysed by Optical and Scanning Electron Microscopic (SEM) whereas presence of reinforcement particles such SiC and TiB2 along with intermetallic phases Mg2Si and Al5FeSi are confirmed by EDX, XRD and Element Mapping analyses.
Surface roughness and microstructure analysis on drilling of titanium diboride in-situ aluminium metal matrix composite C Rajaravi, U Elaiyarasan, B Gobalakrishnan, R Ganapathy Srinivasan Surface Topography Metrology and Properties, 2022 Aluminium and its alloys are widely used for fabricating components are used in aircraft, automobile, defence and structural applications. Due to its light weight and high strength, it is applied in the various commercial purposes such as window, doors, construction member etc. However, machining of aluminium alloys using conventional machining methods is difficult. In this present investigation, an endeavour has been made to drill TiB2 in situ aluminium metal matrix composite alloy developed using stir casting method. During the casting two different salts namely K2TiF6 and KBF4 are added with matrix materials to form TiB2. The paper is studied the surface roughness (SR) of drilled TiB2 in situ aluminium metal matrix composite viz speed, feed rate and TiB2 addition. Empirical relationship is developed for SR in order to identify the dominating factors. The percentage contribution of SR is 96.35% that showed the empirical model is adequate. The normal probability plot showed the points of residuals are equally distributed over the straight line. The lack of fit value was 3.65 which is less than the standard point. Therefore, the SR model is satisfactory. SR increased with increasing of speed, feed rate and addition of TiB2. The removal of TiB2 particles causes small pits and voids due to the inclusion of reinforcement. The minimum SR was achieved at lowest speed (1260 rpm), feed rate (0.05 mm rev−1) and TiB2 addition (2%). As speed and feed increased, the surface hardness increased.
Analysis of mechanical properties of cold extruded Al 6061 TiB2MMCs and validated for finite element analysis B. Gobalakrishnan, C. Rajaravi, Gobikrishnan Udhayakumar, P.R. Lakshminarayanan, M. Sivanesh Prabhu Materials Today Proceedings, 2020 In the present work, synthesized composite of aluminium matrix composite reinforced with 8 wt% of TiB2 particles and the base Al6061 alloy were fabricated by stir casting method and secondary worked with cold extrusion die. The billets were prepared for the dimension of diameter 18 mm and length 90 mm. specimens were subjected to cold extrusion process with extrusion ratio of 1.2656 under laboratory condition. The mechanical properties such as Rockwell hardness tensile strength were determined as per the ASTM standard E08-16 and ASTM standard ASTM E18-15. It was found that the extruded composites revealed superior mechanical properties as compared to as-cast composites and base metal. To determine the particle distribution and its size, scanning electron microscope (SEM) and optical microscope (OM) have been carried out for microstructural study. Also, Energy Dispersive X-ray (EDX) and X-ray Diffractometer (XRD) were studied to confirm the presence of TiB2 particles in the fabricated samples. The experimental results were validated through Finite Element Analysis (FEA) using ANSYS 14. The predicted mechanical results attained by FEA are in good agreement with the experimental results.
