Excess Volume at Grain Boundaries in hcp Metals

TL;DR

This paper investigates the excess volume at grain boundaries in hcp metals using first-principles calculations, revealing significant variations depending on boundary type and metal, which impact material properties.

Contribution

It provides the first-principles analysis of excess volume at specific grain boundaries in multiple hcp metals, highlighting boundary-dependent differences.

Findings

Vanishing excess volume at (10-12) twin boundary in Ti and Zr

Significant excess volume at basal-prismatic boundaries in Zn, Cd, and Zr

Boundary type influences excess volume magnitude in hcp metals

Abstract

The excess volume associated with grain boundaries represents a key structural parameter for the characterization of grain boundaries. It plays a critical role in segregation of impurity and alloy elements to grain boundaries, and influences significantly the mechanical and functional properties of materials. We have carried out first-principles density functional calculations on the atomic structure of the (10-12) coherent twin boundary in hexagonal close packed (hcp) Ti and Zr and the basal-prismatic boundary in Zn, Cd, and Zr. We find the calculated excess volume has a vanishing magnitude at the (10-12) coherent twin boundary in Ti and Zr; whereas it is remarkable at the basal-prismatic boundary in Zn, Cd, and Zr.