Fabrication of Functionally Graded Metal Matrix composite using Multi-Pass Friction Stir Processing

Abstract

Abstract-Functional Graded Materials (FGM) are innovative materials in which final properties varies gradually with dimensions. It is the recent development in traditional composite materials which retains their strengths and eliminates their weaknesses. It can be formed by varying chemical composition, microstructure or design attributes from one end to other as per requirement.. Previous investigations show that various techniques such as powder metallurgy, centrifugal method, vapor deposition techniques, solid freeform fabrication methods and friction stir processing etc. have been used to fabricate the FGM. In order to overcome the control over the composition, the present study presents a method to fabricate Functional Graded Material using Friction Stir Processing (FSP) and hole drilling electrical discharge machine (EDM). Holes are drilled on an aluminum plate and filled with Alumina nano-particles of size (<50nm) and stirred using FSP. A mathematical model for positioning of holes in order to acquire a range of maximum to minimum composition of nano particles over a given length is presented. By aligning FSP seem tool center to hole center, multi-pass FSP is carried out to understand the material flow and mixing. The hardness variation along the direction parallel to the surface and perpendicular to the surface and along the depth is measured. The mathematical model is applied to different combinations of composition ranges and is evaluated under different conditions.