Microscale deformation of intermetallic-Mg interface under shear loading

TL;DR

This paper introduces a novel microshear testing method to evaluate the shear strength and deformation behavior of intermetallic-Mg interfaces in Mg-Al-Ca alloys, revealing ductile deformation at room temperature.

Contribution

It presents a new microshear geometry and applies finite element modeling and in situ testing to analyze intermetallic-Mg interface strength and deformation mechanisms.

Findings

Interface shear strength of ~136 MPa

Ductile deformation observed at room temperature

Optimized specimen dimensions via finite element modeling

Abstract

While intermetallic (IM)-metal interfaces in metallic alloys are critical for tuning mechanical properties, they can also act as failure sites, underscoring the importance of determining their strength. This study reports on a novel microshear geometry, and demonstrates its applicability for testing the strength and deformation behavior of IM-metal interfaces in Mg-Al-Ca alloys, a key material for light weight automotive applications. The shear tests are applied to a model bi-layered system grown by magnetron sputtering, comprising of a CaMg2 film deposited onto a Mg layer. A parametric study was performed using finite element modeling to optimize the specimen dimensions. Subsequently, in situ microshear tests conducted inside a scanning electron microscope revealed an interface shear strength of ~136 MPa, and provided insights into the stages of deformation progression. Post mortem examination of the sheared interface revealed an irregular surface indicating ductile deformation at room temperature.