%0 Journal Article
%T Fabrication of Hybrid Surface Composite through Friction Stir Processing and Its Impression Creep Behaviour
%A S. Prakrathi
%A M. Ravikumar
%A K. R. Udupa
%A K. Udaya Bhat
%J ISRN Materials Science
%D 2013
%R 10.1155/2013/541762
%X Al-Ni in situ surface composites were fabricated by friction stir processing method. Friction stir processing produced a composite with nickel and NiAl3 as reinforcement particles in aluminium matrix. The particles were fine and were in the submicrometer size range. The separation distance between the particles was very small. Impression creep experiments were conducted on the samples both at friction stir zone and base material zone at various temperatures. Steady state creep rates were estimated, and activation energy for creep was calculated. It is observed that the friction stir zone offered a higher creep resistance compared to the base metal zone. Higher creep resistance is attributed to the dissolution of nickel atoms into aluminium matrix and the presence of fine nickel particles and NiAl3 precipitates. The measured activation energy indicated that the associated creep mechanism is the dislocation creep in the temperature range of 30¨C150¡ãC, both in friction stir zone and base metal zone. At higher temperatures (150¨C180¡ãC) the diffusion creep mechanism is suggested. 1. Introduction Aluminum and its alloys have versatile properties which make them suitable for use in a variety of applications [1]. In many of the applications, the surface needs to have better mechanical properties like improved strength and better hardness. Having a metal matrix composite at the surface is one of the optiones to have better resistance to wear, improved hardness, and even to an extent high-temperature stability at the surface [2]. Friction stir processing (FSP) is a new metal working method for producing surface composite. It is based on the concept of friction stir welding (FSW) [3]. During friction stir processing, the stirred material undergoes severe plastic deformation. The material flow associated with stirring and severe plastic deformation can be used for bulk alloy modification by the mixing of second elements, mixing followed by the precipitation of second phases, distribution of fine particles of second element, increased density of defects, and so forth. As a result, the stirred zone becomes a metal matrix composite with an improved hardness and wear resistance [4]. Arora et al. [5] have reviewed composite fabrication using FSP route. Mishra et al. [6] have used this route to make a surface composite on AA 5083 alloy with 0.7£¿¦Ìm SiC particles. Shafiei-Zarghani et al. [7] and Mahmoud et al. [8] have incorporated Al2O3 and SiC particles to substrates like Al, Cu, and Fe alloys and observed an improvement in the abrasion and wear resistance of the surface
%U http://www.hindawi.com/journals/isrn.materials.science/2013/541762/