Achieving a Compatible Tensile Strength and Ductility of Bulk Ultrafine Grained Al by Spark Plasma Sintering Plus Annealing

Abstract

A bulk ultrafine grained Al sample fabricated by spark plasma sintering of a mechanically milled nanocrystalline Al powder fractured prematurely at a tensile stress of 223 MPa, with the cracks initiating and propagating along interparticle boundaries (IPBs). However, annealing of the as-SPSed sample drastically improved the tensile mechanical properties, achieving a uniform elongation of 6.5% as well as a high yield strength of 183 MPa and ultimate tensile strength of 230 MPa, thanks to the formation of coarse grains and removal of nanopores in the IPB regions.

Keywords: Spark plasma sintering, Annealing, Interparticle boundaries, Abnormal grain growth, Mechanical properties