Characterization of structure and mechanical properties of MoSi{sub 2}-SiC nanolayer composites
- Los Alamos National Lab., NM (United States)
- Technical Research Centre of Finland, Espoo (Finland)
A systematic study of structure-mechanical properties relation is reported for MoSi{sub 2}-SiC nanolayer composites. Alternating layers of MoSi{sub 2} and SiC were synthesized by DC magnetron and rf-diode sputtering, respectively. Cross-sectional transmission electron microscopy was used to examine three distinct reactions in the specimens when exposed to different annealing conditions: Crystallization and phase transformation of MoSi{sub 2}, crystallization of SiC, and spheroidization of the layer structures. Nanoindentation was employed to characterize the mechanical response as a function of structural changes. As-sputtered material exhibits amorphous structures in both types of layers and has a hardness of 11 GPa and a modulus of 217GPa. Subsequent heat treatment induces crystallization of MoSi{sub 2} to form the C40 structure at 500C and SiC to form the a structure at 700C. The crystallization process is directly responsible for hardness and modulus increase in multilayers. A hardness of 24GPa and a modulus of 340GPa can be achieved through crystallizing both MoSi{sub 2} and SiC layers. Annealing at 900C for 2h causes the transformation of MoSi{sub 2} into the C11{sub b} structure, as well as spheroidization of the layering to form a nanocrystaulline equiaxed microstructure. A slight degradation in hardness but not in modulus is observed accompanying the layer break-down.
- Research Organization:
- Los Alamos National Lab., NM (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 10112648
- Report Number(s):
- LA-UR-93-4274; CONF-931108-33; ON: DE94004982
- Resource Relation:
- Conference: Fall meeting of the Materials Research Society (MRS),Boston, MA (United States),29 Nov - 3 Dec 1993; Other Information: PBD: [1993]
- Country of Publication:
- United States
- Language:
- English
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