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Title: Fractographic finger printing of proton-irradiation-induced disordering and amorphization of intermetallic compounds

The intermetallic compounds NiTi, NiTi/sub 2/, CuZr, CuTi/sub 2/, and Zr/sub 3/Al were irradiated by 2 MeV protons at various temperatures between --175 /degree/C and --44 /degree/C to a fluence of 1.9/times/10/sup 22/ H/sup +//m/sup 2/. Transmission electron microscopy, electron diffraction, and x-ray diffraction were used to evaluate the extents of disordering and amorphization induced by irradiation in the samples. Both phenomena progressed to varying extents in the five compounds, depending on the irradiation temperature and dose. It was observed that the C-A transition began before the degree of long-range order was reduced significantly, and that the amorphous phase nucleated homogeneously throughout the crystalline matrix. A major finding of the current investigation is that the technique of scanning electron fractography provides a useful correlation between the features of the fractured surfaces and the microstructural alterations induced by the proton irradiations. When amorphization is complete the fracture surfaces are either featureless (e.g., NiTi/sub 2/) or contain branching features resembling river patterns. In some cases (especially in CuZr) these are similar to the markings seen on the surface of fractured amorphous ribbons produced by melt-spinning. In general, however, there is not a particularly good correlation between the features on the fracture surfacesmore » of the irradiated and melt-spun ribbons. When the microstructure consists of amorphous regions embedded in a partially disordered crystalline matrix, there is consierable evidence for irradiation-induced ductility. In such cases, exemplified by the results on NiTi and Zr/sub 3/Al, the fracture surfaces contain dimples, characteristic of ductile fracture, suggesting that disordering promotes ductility.« less
Authors:
; ; ;
Publication Date:
OSTI Identifier:
5948340
Resource Type:
Journal Article
Resource Relation:
Journal Name: J. Mat. Res.; (United States); Journal Volume: 4:3
Research Org:
Department of Materials Science and Engineering, University of California, Los Angeles, California 90024 (US)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ALUMINIUM COMPOUNDS; PHYSICAL RADIATION EFFECTS; COPPER COMPOUNDS; NICKEL COMPOUNDS; TITANIUM COMPOUNDS; ZIRCONIUM COMPOUNDS; DOSE RATES; ELECTRON DIFFRACTION; INTERMETALLIC COMPOUNDS; LOW TEMPERATURE; MEV RANGE 01-10; ORDER-DISORDER TRANSFORMATIONS; PROTONS; TEMPERATURE DEPENDENCE; TRANSMISSION ELECTRON MICROSCOPY; X-RAY DIFFRACTION; ALLOYS; BARYONS; COHERENT SCATTERING; DIFFRACTION; ELECTRON MICROSCOPY; ELEMENTARY PARTICLES; ENERGY RANGE; FERMIONS; HADRONS; MEV RANGE; MICROSCOPY; NUCLEONS; PHASE TRANSFORMATIONS; RADIATION EFFECTS; SCATTERING; TRANSITION ELEMENT COMPOUNDS 360106* -- Metals & Alloys-- Radiation Effects; 360102 -- Metals & Alloys-- Structure & Phase Studies