Observation of Plastic Deformation Behavior of Mg-Y Alloy Single-Crystals by Using In-Situ Brinell Indentation

Abstract

In order to understand a plastic deformation behavior of pure Mg and Mg-Y alloy single-crystals under a complex stress condition, newly established in-situ Brinell indentation was conducted. The deformation morphology on the upper surfaces of the specimen around the indent could not been sufficiently observed by the previously reported in-situ indentation methods using an optically transparent indenter due to refraction of rays at a surface of the indenter. In this study, the space between the indenter and the specimen surface are filled with immersion liquids such as silicone oil and kerosene. This technique enables to observe the specimen surface during indentation. Using in-situ Brinell indentation on pure Mg and Mg-Y alloy single-crystals, it is found that the shape of the indents on them are not circle but elliptic even during the loading. The aspect ratio of the indents decreases with increasing Y content. Moreover, occurrences of plastic deformation mechanisms around and beneath the indent could be observed during loading and unloading process by using the in-situ Brinell indentation method.

Fig. 2

The in-situ images of （a） pure Mg, （b） Mg-1.3 at.％Y and （c） Mg-2.3 at.％Y single-crystals during loading process with n_r/n_i＝0.85. （d） An in-situ image processed to measure the major and the minor diameters of the indent on pure Mg single-crystal at 9.8 N.