Ordering and the micromechanics of Ti-7Al

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

卷:650

Article

Radecka, Anna¹  Coakley, James^2,3  Jones, Ian P.⁴  Rugg, David⁵  Lindley, Trevor C.¹  Dye, David¹ 

[1] Univ London Imperial Coll Sci Technol & Med, Royal Sch Mines, Dept Mat, London SW7 2BP, England

[2] Univ Cambridge, Dept Mat Sci & Met, Cambridge CB3 OF3, England

[3] Northwestern Univ, Dept Mat Sci & Engn, Evanston, IL 60208 USA

[4] Univ Birmingham, Sch Met & Mat, Birmingham B15 2TT, W Midlands, England

[5] Rolls Royce PLC, Derby DE24 8BJ, England

关键词: Titanium alloys;    Neutron scattering;    Ordering;   

DOI  :  10.1016/j.msea.2015.09.070

来源: Elsevier

【 摘 要 】

The evolution of intergranular lattice strain in the a titanium alloy Ti-7Al wt% was characterised using in situ time-of-flight (TOF) neutron diffraction during room temperature tensile loading. Samples were aged to promote ordering and the formation of nanometre-scale alpha(2) (Ti3Al). On ageing, at 550 degrees C and 625 degrees C, dislocations were observed to travel in pairs, and in planar arrays, which has been attributed to the presence of ordering. A slight change in c/a was observed, from 1.6949 to 1.6945, and a slight increase in the macroscopic modulus. However, no changes were observed in the residual lattice strains, which are the grain-orientation average elastic strains produced by plasticity. Therefore it is inferred that the changes in deformation mechanisms caused by ordering that result in an enhanced vulnerability to dwell fatigue affect primarily the extent of slip localisation. The overall strain distributions between grains in different orientations are not changed. (C) 2015 Elsevier B.V. All rights reserved.

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