Mechanical properties of nanostructured and ultrafine-grained iron alloys produced by spark plasma sintering of ball milled powders

Spark plasma sintering of an iron-based powder has been studied. The powder was prepared with three different microstructures: fully annealed (grain size d larger than 10 mu m), nanometer sized (d similar to 30 nm) and nanometer sized with silica nanoparticles along grain boundaries (d similar to 20 nm).Spark plasma sintering was carried out at varying pressure (30-60 MPa) and temperature (from 800 to 900 degrees C). Shrinkage during sintering was studied by means of densification curves. Near fully dense or fully dense samples were consolidated; depending on the sintering temperature and on thermal stability of the powder, nanostructured, ultrafine-grained and fine grained materials were obtained. Tensile testing demonstrates that the finer the microstructure, the harder and the stronger is the material, and the lower is the uniform deformation. (c) 2007 Elsevier B.V. All rights reserved.