Stacking faults and the {\gamma}-surface on {1-101} pyramidal planes in {\alpha}-titanium

TL;DR

This study uses first principles calculations to analyze the gamma-surface and stacking faults on pyramidal planes in alpha-titanium, revealing stable faults and proposing a new dislocation dissociation mechanism.

Contribution

It provides the first detailed gamma-surface analysis for pyramidal planes in alpha-titanium and proposes a novel dissociation pathway for c+a dislocations.

Findings

Identified two stable intrinsic stacking faults with low energies.

Disproved the possibility of dissociation into two partials with (c+a)/2 Burgers vector.

Suggested a new dissociation mechanism involving three partial dislocations.

Abstract

Using first principles methods we calculated the entire {\gamma}-surface of the first order pyramidal planes in {\alpha}-titanium. Slip on these planes involving dislocations with c + a dislocations is one means by which {\alpha}-titanium polycrystals may supplement slip on prism planes with a-type Burgers vectors to maintain ductility. We find two stable intrinsic stacking faults with relatively small energies. We show that dissociation of c + a dislocations into two dislocations with Burgers vectors (c + a)/2 is not possible in {\alpha}-titanium because there is no stable stacking fault at (c + a)/2. Instead we propose a possible dissociation of a c + a dislocation into three partial dislocations separated by the two intrinsic faults we have identified.