In Situ Micromechanical Testing for Single Crystal Property Characterization

An in situ method to fully characterize the single crystal properties for polycrystalline alloys is developed using microscale experimental and analysis techniques. The developed method can be applied to metallic engineering alloys that do not exist in single crystal form. Thus using this technique, testing and analysis on polycrystalline samples can yield the single crystal elastic and plastic properties required as input to micro- and mesoscale computational models such as those which rely on crystal plasticity theory. Compression and shear experiments are conducted on single crystal specimens of various crystallographic orientations. Analytical and numerical analysis of the experimental results yields a set of equations that can be solved for the single crystal elastic parameters. This novel methodology is demonstrated to produce reasonable elastic property prediction results for an aerospace aluminum lithium alloy, AA2070. Details regarding the experiments and analysis are provided to facilitate application of the technique to a wide range of polycrystalline material systems and properties.