Microstructure, hardness and wear properties of functionally graded Cu-Sn-Ni alloy developed by friction stir processing

摘要

Recently Friction Stir Processing (FSP) has been widely used as an effective technique for surface and subsurface modification. It is used for modifying microstructure of a metal in order improve its property. Single FSP may lead to improved formability of the metal as a result of significant grain refinement and homogenization. This improvement in formability is mainly observed at elevated temperature. The investigation aims to develop a surface modified, functionally graded Cu-Sn bronze alloy with the addition of Ni by Friction Stir Processing (FSP). Evaluation of microstructure, hardness and wear properties of the developed alloy was conducted. Nickel with varying coating thicknesses was applied on the bronze substrate and the surface modification was carried out. Hardness and wear rate of the modified layer were measured using a micro-hardness tester and a pin-on-disc wear tester, respectively. The Ni concentration profiling was done using EDAX. A layered functionally graded bronze alloy was obtained after the FSP. A fine grained microstructure was observed in the modified layer. The hardness as well as wear resistance was found to improve as a result of nickel addition by FSP. The coefficient of friction remains constant irrespective of the hardness.