Analysis of crystallographic slip and grain boundary sliding in a Ti-45Al-2Nb-2Mn (at%)-0.8 vol%TiB2 alloy by high temperature in situ mechanical testing

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:606

Article

Munoz-Moreno, R.^1,2  Ruiz-Navas, E. M.²  Boehlert, C. J.^1,3  Llorca, J.^1,4  Torralba, J. M.^1,2  Perez-Prado, M. T.¹ 

[1] IMDEA Mat Inst, Madrid 28906, Spain

[2] Univ Carlos III Madrid, Dept Mat Sci & Engn, Leganes 28911, Spain

[3] Michigan State Univ, Dept Chem Engn & Mat Sci, E Lansing, MI 48824 USA

[4] Univ Politecn Madrid, Dept Mat Sci, Madrid 28040, Spain

关键词: In situ testing;    EBSD;    TiAl;    Crystallographic slip;    Grain boundary sliding;    Schmid law;   

DOI  :  10.1016/j.msea.2014.03.078

来源: Elsevier

【 摘 要 】

This work aims to contribute to a further understanding of the fundamentals of crystallographic slip and grain boundary sliding in the gamma-TiAl Ti-45Al-2Nb-2Mn (at%)-0.8 vol%TiB2 intermetallic alloy, by means of in situ high-temperature tensile testing combined with electron backscatter diffraction (EBSD). Several microstructures, containing different fractions and sizes of lamellar colonies and equiaxed gamma-grains, were fabricated by either centrifugal casting or powder metallurgy, followed by heat treatment at 1300 degrees C and furnace cooling, in situ tensile and tensile-creep experiments were performed in a scanning electron microscope (SEM) at temperatures ranging from 580 degrees C to 700 degrees C. EBSD was carried out in selected regions before and after straining. Our results suggest that, during constant strain rate tests, true twin gamma/gamma interfaces are the weakest barriers to dislocations and, thus, that the relevant length scale might be influenced by the distance between non-true twin boundaries. Under creep conditions both grain/colony boundary sliding (G/CBS) and crystallographic slip are observed to contribute to deformation. The incidence of boundary sliding is particularly high in gamma grains of duplex microstructures. The slip activity during creep deformation in different microstructures was evaluated by trace analysis. Special emphasis was placed in distinguishing the compliance of different slip events with the Schmid law with respect to the applied stress. (C) 2014 Elsevier B.V. All rights reserved.

【 授权许可】

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