Regensburg 2000 – scientific programme
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M: Metallphysik
M 1: Plastizität I
M 1.5: Talk
Monday, March 27, 2000, 11:15–11:30, H16
Texture induced plastic anisotropy of NiAl polycrystals — •W. Skrotzki1, R. Tamm1, C.-G. Oertel1, B. Beckers2, H.-G. Brockmeier3, and G. Dresen4 — 1Institut f"ur Kristallographie und Festk"orperphysik, Technische Universit"at Dresden, D-01062 Dresden — 2Institut f"ur Metallkunde und Metallphysik, RWTH Aachen, Kopernikusstra"se 14, D-52074 Aachen — 3GKSS-Forschungszentrum Geesthacht GmbH, Max- Planck-Stra"se 1, D-21494 Geesthacht — 4Geoforschungszentrum Potsdam, Telegrafenberg, 14473 Potsdam
Compression of NiAl polycrystals was carried out at room temperature under atmospheric pressure as well as 0.4 Gpa confining pressure at a strain rate of about 10−4 s−1. The stress-strain curves show that the strength as well as the work-hardening rate is generally higher when deformed under hydrostatic pressure. Moreover, there is a strong plastic anisotropy, that is, samples having a ⟨ 100⟩ crystallographic preferred orientation parallel to the compression axis are much harder than those having ⟨ 110⟩ and ⟨ 111⟩. Similarly, the frequency of microcracking shows the same tendency. It seems that the microcracks in the samples deformed under confining pressure mainly result from internal stresses released after unloading. The strength of the differently textured samples correlates well with the Taylor energy calculated. These calculations also explain for certain textures the deviation from a homogeneous shape change during compression via plane strain deformation.