Comprehending Interphase Shearing Behavior within a Bulk Cu-Nb Alloy Using Micromechanical Testing

Abstract

Understanding the deformation mechanisms behind microstructural evolution during shear loading has been a long-standing area of interest. However, establishing a connection between microstructure, mechanical properties, and the extent of shear deformation is challenging and requires refined experimental approaches. Micro-shear testing offers a controlled method to introduce shear into small volumes of material, allowing for detailed site-specific microstructural characterization. In this work, we investigated the shear deformation behaviour and properties of copper (Cu) matrix and at copper-niobium (Cu-Nb) interfaces using micro-shear testing. The yielding under shear loading is dependent on the orientation of the interfaces. Intuitively, when the interface is parallel to the shear direction, the flow stresses are lower compared to when it is perpendicular. Transmission electron microscopy examination shows stacking faults and twins dominating the deformation on the Cu side while limited dislocation activity in the neighboring Nb crystal. Moreover, an amorphous layer was observed at the Cu-Nb interface which likely formed after shear deformation. In summary, our study provides an understanding of the shear deformation behavior of immiscible systems at a small scale which will eventually be helpful in predicting the behavior of these alloys during solid phase processing.

Keywords: deformation, interfaces, Micromechanical testing, forced mixing, immiscible alloys, amorphization