Analysis of local microstructure after shear creep deformation

0354833 - ÚFM 2011 RIV GB eng J - Journal Article
Peter, D. - Viswanathan, G.B. - Dlouhý, Antonín - Eggeler, G.
Analysis of local microstructure after shear creep deformation.
Acta Materialia. Roč. 58, č. 19 (2010), s. 6431-6443. ISSN 1359-6454. E-ISSN 1873-2453
R&D Projects: GA ČR GA106/07/0762
Institutional research plan: CEZ:AV0Z20410507
Keywords : Titanium aluminides * Shear creep deformation * Transmission electron microscopy * Dislocations * Twinning
Subject RIV: JG - Metallurgy
Impact factor: 3.781, year: 2010

The present work characterizes the microstructure of a hot-extruded Ti–45Al–5Nb–0.2B–0.2C (at.%) alloy with a fine-grained duplex microstructure after shear creep deformation (temperature 1023 K; shear stress 175 MPa; shear deformation 20%). Diffraction contrast transmission electron microscopy (TEM) was performed to identify ordinary dislocations, superdislocations and twins. The microstructure observed in TEM is interpreted taking into account the contribution of the applied stress and coherency stresses to the overall local stress state. Lamellar c grains can be in soft and hard orientations with respect to the resolved shear stress provided by the external load. The presence of twins can be rationalized by the superposition of the applied stress and local coherency stresses. The presence of superdislocations in hard c grains represents indirect evidence for additional contributions to the local stress state associated with stress redistribution during creep.
Permanent Link: http://hdl.handle.net/11104/0193748