Bonding effects on the slip differences in the B1 monocarbides.

Area of Science:

• Materials Science
• Solid-State Physics
• Crystallography

Background:

• Plasticity differences in materials are typically linked to changes in crystal symmetry or interatomic bond strength.
• B1 monocarbides present a unique case where slip plane variations occur despite identical crystal structures and similar bonding.

Purpose of the Study:

• To experimentally determine and theoretically explain the differing slip planes in Hafnium carbide (HfC) and Tantalum carbide (TaC).
• To investigate the underlying mechanisms responsible for the observed plasticity differences in these transitional metal carbides.

Main Methods:

• Experimental observation of slip planes in HfC and TaC at low temperatures.
• Density functional theory (DFT) calculations to model and rationalize the slip behavior.

Main Results:

• Experimental data confirms HfC slips on {110} planes.
• Experimental data confirms TaC slips on {111} planes.
• DFT calculations reveal intrinsic stacking fault formation on {111} planes and Shockley partials in TaC, alongside enhanced metallic bonding due to valence electron configuration.

Conclusions:

• The distinct slip planes in HfC and TaC, despite structural similarities, are attributed to differences in stacking fault energy and electronic structure.
• Enhanced metallic bonding and the propensity for intrinsic stacking fault formation in TaC dictate its {111} slip behavior, differentiating it from HfC's {110} slip.