Electronic Thesis and Dissertation Repository

Degree

Master of Engineering Science

Program

Mechanical and Materials Engineering

Supervisor

Robert. J. Klassen

Abstract

In this thesis, we present nano-indentation measurements performed to quantify the increase in hardness as a result of He+ and Fe4+ implantation in both Inconel 800H and AISI 310 alloys. After annealing, the softening rate of He+ and Fe4+ implanted samples were compared, and it is found that Ni can slow the helium diffusion. Thermal activation energy Q characterizing this process was similar to the computed thermal activation energy QHe for interstitial helium diffusion within pure nickel. Indentation hardness tests were also performed at various indentation strain rates, to further study the effect of implanted helium as an obstacle to plastic deformation. It was observed, for both AISI 310 and Inconel 800H, the strain rate sensitivity m decreases, and the activation volume V* increases significantly after annealing. This suggests that helium defects (voids or bubbles) within the metal become more stable with annealing, as they tend to form bigger bubbles in the grain boundaries.