Quantitative Evaluation of Spherical Indentation Behavior in Pure Magnesium Single Crystals Using Instrumented Microhardness Tests

Indentation tests were performed on 14 pure magnesium single crystals whose crystal orientations were changed every 15 degrees using an instrumented microhardness tester equipped with a spherical indenter. The dependence of the indentation behavior on the crystal orientation was quantitatively evaluated using load-penetration depth (P-h) curves. The indentation morphology depended on the crystal orientations and varied from circular to elliptical. Basal slips and {1012} twins were observed around all the indentations except (0001) indentation. {1012} twins with different elongated directions, 'twin variants', were also observed around indentations. The number of elongated directions of {1012} twins depended on the crystal orientations of indentation planes. The dependence was analyzed using the Schmid factor, and the distribution of the number of elongated directions of {1012} twins was shown on a standard stereographic triangle. The distribution, inclination of P-h curves, and indentation depths were systematically obtained and analyzed. Using the instrumented spherical indentation test and the systematic data, crystal orientation analysis can be performed with high accuracy.