Date of Graduation

2005

Document Type

Thesis

Degree Type

MS

Committee Chair

Bruce S. Kang

Committee Chair

Bruce S. Kang

Abstract

Molybdenum based alloys are ductilized by dispersing MgAl2O4 or NiAl2O4 spinel particle. These additions of spinel particles getter impurities, such as Nitrogen, from the base alloys which render its ductility. The introduction of fine dispersions has also been postulated to improve ductility in body centered cubic (BCC) metals such as Mo, by acting as a dislocation source or reducing dislocation pile ups at grain boundaries. The spinel particles, on the other hand, would also act as local notches, crack initiation sites, which are detrimental to the ductilization. Further improvement of material processing, therefore, is very important. The objective of this research is to study the thermomechanical properties of spinel (MgAl2O4) dispersed molybdenum alloys and the segregation (gettering) of impurities to the oxide dispersion/Mo interfaces. Thermal cycling tests between temperatures of 650°C and 1000°C were performed. A series of post-mortem microstructure evaluations were conducted using X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), and Qualitative/Quantitative Energy Dispersive Spectroscopy (EDS) techniques on SEM to study the effect of dispersed spinel particles on the Molybdenum matrix.

Download

Share

COinS