A review on properties and microstructure of micro-extruded product using SPD and as-cast material

Abstract

Micromanufacturing has wide application in the development of micro-products, but these methods are limited in developing desired properties such as dimensional tolerance, surface texture and electromechanical properties. Deformation is one of the techniques where such limitations on micro-products can be overcome based on the principle of grain refinement theory. The product developed through subtractive and additive method reveals coarse grain microstructure, whereas ultrafine grains (UFGs) are observed in the severe plastic deformation (SPD) process. Equal-channel angular pressing (ECAP) is one of the best SPD techniques to produce UFG up to a nanometre. As-cast micro-extruded product that contains coarse grains seems to be inhomogeneous, having wide deviation of physical and mechanical properties throughout its volume. ECAP-based micro-extruded product is homogeneous and has uniform physical and mechanical properties. The present review paper discusses about the influence of die geometry, die strength, specimen selection, frictional condition, temperature condition and other boundary conditions on the properties of as-cast and ECAPed extruded material. Similarly, size and direction of grain can alter the mechanical properties based on requirements and type of applications.