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Studying Plasticity in Hard and Soft Nb–Co Intermetallics
Author(s) -
Korte Sandra,
Clegg William J.
Publication year - 2012
Publication title -
advanced engineering materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.938
H-Index - 114
eISSN - 1527-2648
pISSN - 1438-1656
DOI - 10.1002/adem.201200175
Subject(s) - materials science , intermetallic , flow stress , plasticity , brittleness , monoclinic crystal system , anisotropy , crystallography , slip (aerodynamics) , shear (geology) , condensed matter physics , laves phase , metallurgy , composite material , thermodynamics , microstructure , crystal structure , alloy , physics , optics , chemistry
It is shown that micropillar compression can be used to study the plastic flow behavior of both a hard, brittle cubic Laves phase, NbCo 2 , and a related monoclinic compound, Nb 2 Co 7 , which is known to be softer, but is also brittle and has, so far, only been prepared in a fine‐grained form. Flow in the Laves phase occurs at a shear stress of 3.1 GPa on the $\left\langle {0{\bar {1}}{\bar {1}}} \right\rangle $ {111} slip system, consistent with previous observations and estimates from hardness measurement. Micropillar compression and electron microscopy of single crystals of Nb 2 Co 7 indicates that flow takes place parallel to the (001) plane, with $\left\langle {100} \right\rangle $ and $\left\langle {110} \right\rangle $ type Burgers vectors, at a critical resolved shear stress between 0.1 and 0.5 GPa. It is shown that this is much less than predicted by hardness measurements, consistent with the idea that the hardness of plastically anisotropic materials is determined by flow on the hardest operating slip system.