Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7882646 | Acta Materialia | 2014 | 19 Pages |
Abstract
Free-standing Pt-aluminide (PtAl) bond coats exhibit a linear stress-strain response under tensile loading and undergo brittle cleavage fracture at temperatures below the brittle-to-ductile transition temperature (BDTT). Above the BDTT, these coatings show yielding and fail in a ductile manner. In this paper, the various micromechanisms affecting the tensile fracture stress (FS) below the BDTT and yield strength (YS) above the BDTT in a PtAl bond coat have been ascertained and quantified at various temperatures. The micromechanisms have been identified by carrying out microtensile testing of stand-alone PtAl coating specimens containing different levels of Pt at temperatures between room temperature and 1100 °C and correlation of the corresponding fracture mechanisms with the deformation substructure in the coating. An important aspect of the influence of Pt on the tensile behavior, slip characteristics, FS/YS and BDTT in the PtAl coating has also been examined. The addition of Pt enhances the FS of the coating by Pt solid solution strengthening and imparts a concomitant increase in fracture toughness and yet causes a significant increase in the BDTT of the coating.
Related Topics
Physical Sciences and Engineering
Materials Science
Ceramics and Composites
Authors
Md. Zafir Alam, S.V. Kamat, V. Jayaram, D.K. Das,