Asymmetry in structural and thermo-mechanical behavior of intermetallic NiAl nanowire under tensile/compressive loading: A molecular dynamics study

作者：Sutrakar Vijay Kumar; Mahapatra D Roy^*

来源：Intermetallics, 2010, 18(8): 1565-1571.

DOI：10.1016/j.intermet.2010.04.009

• Nanostructured intermetallics
• Phase transformation
• Twinning
• Work hardening
• Simulations
• atomistic

The asymmetric stress strain behavior under tension/compression in an initial < 100 > B(2)-NiAl nanowire is investigated considering two different surface configurations i.e., < 100 >/(0 1 0) (0 0 1) and < 100 >/(0 1 1) (0 - 1 1). This behavior is attributed to two different deformation mechanisms namely a slip dominated deformation under compression and a known twinning dominated deformation under tension. It is also shown that B2 -> BCT (body-centered-tetragonal) phase transformation under tensile loading is independent of the surface configurations for an initial < 100 > oriented NiAl nanowire. Under tensile loading, the nanowire undergoes a stress-induced martensitic phase transformation from an initial B2 phase to BCT phase via twinning along {110} plane with failure strain of similar to 0.30. On the other hand, a compressive loading causes failure of these nanowires via brittle fracture after compressive yielding, with a maximum failure strain of similar to-0.12. Such brittle fracture under compressive loading occurs via slip along {110} plane without any phase transformations. Softening/hardening behavior is also reported for the first time in these nanowires under tensile/compressive loadings, which cause asymmetry in their yield strength behavior in the stress strain space. Result shows that a sharp increase in energy with increasing strain under compressive loading causes hardening of the nanowire, and hence, gives improved yield strength as compared to tensile loading.

• 出版日期2010-8