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Study of defects in amorphous solids

Thesis/Dissertation ·
OSTI ID:7225200

This research is a fundamental investigation of the mechanical properties and associated defect structures in amorphous solids. Radiation damage, crack propagation, and latent hardening were studies for amorphous materials. Whenever possible, comparisons are made with the behaviors of crystalline materials. A molecular-dynamics simulation of radiation damage in a three dimensional amorphous Lennard-Jones solid was performed. The amorphous structure was examined by calculating volume distribution of Voronoi polyhedra. The production of vacancies and interstitials was observed, but they were unstable. A radiation damage experiment on an amorphous metallic alloy BNi/sub 2/ (Ni/sub 69.2/Cr/sub 6.6/B/sub 13.7/Si/sub 7.9/Fe/sub 2.6/) by bombarding with 70-MeV Ni/sup 58/ ions of +6 charge, showed swelling and ridges on the surface. The swelling did not disappear upon annealing. A transmission electron microscope study of irradiated region did not reveal any void structure as observed in crystalline metals. Fatigue crack propagation was studied for two glassy metallic alloys, Metglas 2705X (Co/sub 72.15/Fe/sub 5.85/Mo/sub 2/B/sub 15/Si/sub 5/) and Metglas 2705Mn (Co/sub 76.05/Fe/sub 1.95/Mn/sub 4/B/sub 12/Si/sub 6/). For the first time an overload effect was observed for an amorphous metallic alloy.

Research Organization:
Rochester Univ., NY (USA)
OSTI ID:
7225200
Country of Publication:
United States
Language:
English