Effect of Porosity on Mechanical Properties of Metal Matrix Composite: An Overview

Abstract

Keliangan di dalam tuangan komposit matriks logam (KML) adalah satu kecacatan yang boleh mempengaruhi kekuatan bahan terutamanya di dalam KML bertetulang partikel. Merujuk kepada kajian lepas, faktor-faktor pembentukan keliangan adalah berpunca daripada gelembung-gelembung udara yang memasuki leburan matriks logam, wap air yang terdapat pada permukaan partikel, gas yang terperangkap semasa proses pencampuran, evolusi hidrogen dan pengecutan tuangan semasa pemejalan. Namun, kebanyakkan kajian menunjukkan punca utama pembentukan keliangan adalah parameter proses tuangan. Kandungan keliangan yang paling minima akan menentukan sifat optimum tuangan KML. Secara umumnya, peningkatan kandungan keliangan akan mengurangkan sifat mekanikal KML seperti kekuatan tegangan, modulus Young, nisbah Poisson dan muatan redaman. Kesan pengurangan ini berlaku disebabkan oleh proses kegagalan yang berpunca daripada kehadiran lompang keliangan. Kata kunci: Keliangan, tuangan kacau, sifat mekanikal, tuangan komposit matriks logam, silikon karbida Pososity in cast metal matrix composite (MMC) has been known as a defect affecting the enhancement of strength, particularly in particle-reinforced MMC. From previous reviews, among the causes of porosity formation are air bubbles entering the melt matrix material, water vapour on the particles surfaces, gas entrapment during mixing process, evolution of hydrogen, and shinkage during solidification. Many studies had revealed that casting parameters are the main factors affecting porosity formation. Optimum properties of cast MMC are attained with least porosity content. Generally, increasing content of pososity will decrease the mechanical properties of MMC such as tensile strength, Young’s modulus, Poisson ratio, and damping capacity. This presence of porosity decreased the mechanical properties of cast MMC as the failure process is initiated from the voids formed. Key words: Porosity, stir casting, mechanical properties, cast metal matrix composite, silicon carbide particle