SOME INVESTIGATIONS ON JOINING OF AA-6061 AND Al BASED MMC'S

Abstract

Aluminium alloys are widely used in aerospace and automobile industries, due to their good mechanical properties and excellent ability, to unify the properties. of ceramic phase with the metallic phase which has been useful in gearing up the extensive research activities all around the world. A metal matrix composite (MMC) is a composite material consists of two or more constituent parts, one being metal. The other material being ceramic or organic compound, when at least three materials are present it is called hybrid composite. • Metal matrix composites (MMCs) usually consist of a low- density Metal, such as aluminum or magnesium, reinforced with particulate or fibers of a ceramic material, such as silicon carbide or graphite. Compared with unreinforced metals, MMCs offer higher specific strength and stiffness, higher operating temperature, and greater wear resistance, as well as the opportunity to tailor these properties for a particular application. • The need for lightweight, high performance, structural materials made them • attractive candidate for aerospace, automobile and consumer related industries, provided the necessary impetus for the development and emergence of MMCs • These materials differ from conventional engineering materials from the viewpoint of homogeneity. • Large majority of these composite materials are metallic materials, phases which can be either continuous in the form of fiber, discontinuous in the form of whisker platelets or particulate reinforcement embedded in a ductile metallic matrix. • MMC'S offer potential for improvement in efficiency, mechanical performance and reliability over the new generation alloys. • In recent years ceramic reinforcement aluminum alloys matrix composites are-_ receiving increasing attention because of their improvements in elastic modulus, strength, structural rigidity, wear resistance and control of physical properties such as density and coefficient of thermal expansion. • These properties are important in automobile and aerospace applications because of the potential for large reduction in weight (20-40%), increase in strength 30-50%, increase in stiffness, increase in wear resistance etc.