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 surfaces 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.
- Research Organization:
- Department of Materials Science and Engineering, University of California, Los Angeles, California 90024 (US)
- OSTI ID:
- 5948340
- Journal Information:
- J. Mat. Res.; (United States), Vol. 4:3
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
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