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M: Metallphysik

M 21: Symposium on Structurally Complex Alloy Phases III (SCAP III)

M 21.1: Vortrag

Donnerstag, 14. März 2002, 14:00–14:30, H16

Dislocations and plasticity of L1₂, L1₀, and B2 intermetallics — •Daniel Caillard — CEMES-CNRS, Toulouse, France

Many intermetallics exhibit an increase of the yield-stress with increasing temperature called “yield-stress anomaly” (YSA). The YSA allows a combination of high strength at high temperature and of sufficiently good fracture toughness at low temperature for industrial applications. The origin of the YSA seems a priori difficult to investigate since it can be observed under quite different conditions and in various situations. However, in-situ experiments and numerical modelling compared with macroscopic data showed that in two cases specific dislocation locking mechanisms are at the origin of the YSA: cross-slip leading to the formation of “incomplete” Kear-Wilsdorf locks in Ni₃Al, with the L1₂ structure, and diffusion in FeAl with the B2 structure. The second origin that relies on less constraining hypotheses is proposed to be the most frequent one. The YSA in other intermetallics is then tentatively interpreted on this basis.