Yield stress anomaly in B2 FeAl
- Tohoku Univ., Sendai (Japan). Inst. for Materials Research
- Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.
The studies on yield stress anomaly of B2 FeAl single crystals are reviewed in this paper. A positive temperature dependence of yield stress, so-called yield stress anomaly, is observed in B2 FeAl in which excess vacancies are fully annealed out. Associated with the anomaly, characteristic asymmetry is found between tension and compression. While the strain-rate sensitivity is almost zero in the temperature range of the yield stress anomaly, the stress relaxation becomes significant with increasing temperature, indicating that a recovery process is thermally activated. It is ascertained by the two-surface trace analysis that slip transition from <111> direction at intermediate temperature to <100> at high temperature occurs around the peak temperature. Even at the peak temperature, in addition, operative slip vector for yielding is confirmed to be predominantly <111> by TEM. Also, it is observed that <111>-type superdislocations are frequently climb-dissociated in the temperature range of the anomaly. APB formation on {l_brace}111{r_brace} plane is energetically favorable, which is in agreement with the Flinn`s calculation for the B2 superlattice that APB energy on {l_brace}111{r_brace} plane is lower than that on {l_brace}110{r_brace} plane. Such an anisotropy of APB energy would offer specific driving force for the climb dissociation on <111> superdislocations. On the basis of the observed results, the anomalous strengthening behavior of B2 FeAl single crystals is discussed.
- Research Organization:
- Oak Ridge National Lab., TN (United States)
- Sponsoring Organization:
- USDOE Office of Energy Research, Washington, DC (United States); Ministry of Education, Science and Culture (Japan)
- DOE Contract Number:
- AC05-96OR22464
- OSTI ID:
- 446406
- Report Number(s):
- CONF-961202--69; ON: DE97003493
- Country of Publication:
- United States
- Language:
- English
Similar Records
Slip band propagation and slip vector transition in B2 FeAl single crystals
Deformation behavior of B2 type aluminides; FeAl and NiAl