Processing, Structure and Properties of Heavily Deformed In Situ Composites
Final rept. 1 Jun 1988-31 May 1991,
VIRGINIA UNIV CHARLOTTESVILLE DEPT OF MATERIALS SCIENCE
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Microstructural stability, particularly stability in heavily deformed in situ composites, has been studied and classified systematically. Mechanisms and avenues for the breakdown of plate like structures have been identified, and the conditions under which the several types of instability take place have been specified. Clarification of the strengthening mechanisms that operate in deformation processed composite materials has been made. Tensile and fracture characteristics of metal-metallic glass laminates have been investigated. Laminate fracture toughnesses are much greater than for the metallic glass. This is due to a crack closing force provided by the metal for which the crack lags behind that in the glass. The toughening mechanism has been described in quantitative as well as qualitative terms. Fundamental modeling of the mechanical alloying process has been made from both a mechanics standpoint and a kinetic one. Experimental studies complement analysis. Amorphization behavior of nickel -- tungsten alloys during mechanical alloying has been systematically investigated, as has the subsequent crystallization behavior of these materials. Consolidation of mechanically alloyed Ni-W and copper -- niobium materials has been investigated. Models of hot isostatic pressing have been used to mimic the densification behavior of mechanically alloyed materials for this process.
- Laminates and Composite Materials
- Metallurgy and Metallography