地表起伏的影响αTi-Mo合金沉淀.pdfVIP

Acta Materialia 50 (2002) 929–941 Surface relief effects of α precipitates in a Ti–Mo alloy H. Guo b, M. Enomoto a,* a Department of Materials Science, Ibaraki University, Hitachi 316-8511, Japan b Formerly graduate student, now Department of Materials Science and Engineering, McMaster University, Hamilton ON, Canada L8S 4L7 Received 25 July 2001; received in revised form 18 October 2001; accepted 23 October 2001 Abstract The characteristics of the formation of surface relief associated with h.c.p. α precipitates in a Ti–Mo alloy were studied by atomic force microscopy coupled with electron back scattering diffraction and three-dimensional morphologi- cal observation. Tent- or inverse tent-shaped relief was formed with normal α plates (thick plates formed often with a ragged interface at smaller undercoolings) progressively to a lesser extent with decreasing temperature. It was replaced entirely by invariant plane strain (IPS) type relief as the plate morphology evolved to black plates (thin straight plates formed at larger undercoolings). In contrast to IPS relief the tilt angles of tent- and inverse tent-shaped relief were often considerably greater than expected from the motion of biatomic structural ledges. There seems to be a marked correlation of relief type with the surface orientation of matrix grains. A phenomenological explanation is presented for unduly large relief angles on the basis of previous theories.  2002 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved. Keywords: Titanium alloys; Atomic force m