Effect of Al{sub 2}Ti phase on plastic behavior in Ti-62.5 at% Al single crystals
The microstructure and plastic deformation behavior in Ti-62.5at.%Al single crystals were investigated focusing on effect of the formation of h- and r-Al{sub 2}Ti precipitates. Crystal structure, morphology and volume fraction of the precipitates depended strongly on the annealing temperature. The r-Al{sub 2}Ti phase precipitated as a plate in the L1{sub 0} matrix containing Al{sub 5}Ti{sub 3} superstructure below 1,200 C, while the h-Al{sub 2}Ti phase appeared at the higher temperature. The r-Al{sub 2}Ti had six-fold periodicity along the c-axis of the L1{sub 0} structure and formed a semi-coherent boundary with the matrix maintaining an orientation relationship with ({l{underscore}brace}101){sub r-Al2Ti}//({l{underscore}brace}101){sub L10}. In contrast, small particles of h-Al{sub 2}Ti with three-fold periodicity along the b-axis were homogeneously distributed in the matrix forming an obscure coherent phase boundary. Yield stress for specimens with a [201] loading axis anomaly increased showing a maximum peak around 800 C and then rapidly decreased. {l{underscore}brace}111{r{underscore}brace}[{l{underscore}angle}110] slip was dominant in the L1{sub 0} matrix and r-Al{sub 2}Ti precipitates at temperatures below the peak, while slip occurred on (001) above the peak temperature. The anomalous strengthening and the change in operative slip system were discussed focusing on the effect of anisotropy of APB energy and formation of Al{sub 2}Ti precipitates.
- Research Organization:
- Osaka Univ., Suita (JP)
- OSTI ID:
- 20001601
- Report Number(s):
- CONF-981104--; ISBN 1-55899-458-0; ISSN 1067-9995
- Country of Publication:
- United States
- Language:
- English
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