Tailored Interfaces for Metal-Matrix Composites-Fundamental Considerations
Abstract
The objective of this research was to investigate the interface properties nee or successful metal matrix composites. Thermodynamic stability of the interface and the phases in the composite, nature of the bonding across the interface, and the energy and structure of the interface were studied. With TiC dispersed in Al prepared by the XD process, atomic resolution electron microscopy showed a sharp interface with large areas of partial coherence. The Al-TiC composite is remarkably ductile even at 15 vol.% TiC loading. This attributed to the ability of the Al to recrystallize at the interface forming semicoherent boundaries and to a high level of metallic binding between Al and Ti in TiC. On holding at 640 C the kinetics of the reaction, 13Al + 3TiC - A14C3 + 3Al3Ti, is rapid enough to be observed. This reaction leads to a substantial increase in strength and modulus but a reduction in ductility. Like steel, parts could be formed in the ductile state and then heat treated to increase hardness and modulus. At still higher temperatures, Al and TiC are the thermodynamically stable phases so no reaction occurs. Four Mg alloy matrix composites were received from Dow Chemical Corp.: Mg-6% Zn with SiC, Mg-3% Ce-l% Mn with SiC, Mg-9% Al-l% Zn with SiC, and Mg-9% Al-l% Zn with A12O3. All particle matrix interfaces appeared to be incoherent.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 28, 1993
- Accession Number
- ADA263048
Entities
People
- Julia R. Weertman
- Morris E. Fine
Organizations
- Northwestern University