2 - Fabrication of ODS Alloys

Abstract

Mechanical alloying (MA) process is the byproduct of research into a different subject. This process was developed to produce an alloy combining the benefits of oxide dispersion strengthening (ODS) with gamma prime precipitation hardening in a nickel-based super alloy intended for gas turbine applications. The purpose of nickel coating was to render the normally unwetted oxide particles wettable by a nickel chromium-based alloy. Early experiments used metal-coated zirconium oxide purchased from outside vendors. Chemical analysis, metallographic analysis, and mechanical property measurements revealed no differences between the inoculated materials and uninoculated alloys. Examination of the inoculants revealed that they were zirconia-coated nickel rather than nickel-coated zirconia. Two of the most important alloy systems to emerge from the mechanical alloying process are based on iron and nickel. The solid-state alloying process for these materials is designed to introduce fine dispersions of yttrium oxide particles. The mixture of metal powders and fine refractory oxide powders are milled together, extruded, and further deformed to achieve the required shape.