改良型顕微インデンテーション法によるMg単結晶及び多結晶における変形挙動のその場観察

抄録

In order to investigate a plastic deformation behavior of Mg single- and poly-crystals under a complex deformation condition, in-situ Brinell indentation, which is referred to as a modified Brinell optical indentation microscopy, using an optically transparent indenter and an immersion liquid is conducted. This method enables to observe the contact area between the specimen and the indenter, and the specimen surface around the contact area during indentation. As the results of the modified Brinell optical indentation microscopy on a Ti-Ni superelastic alloy, it is recognized that not only increasing the contact area during loading process but also decreasing the contact area during unloading process can be observed by this method. Using the modified Brinell optical indentation microscopy on pure Mg single-crystals, it is revealed that the shape of the indents is not circle but elliptic because of difference in the relative activity of each plastic deformation mechanism. Moreover, decreasing the contact area caused by the pseudoelastic behavior during unloading process is not recognized in pure Mg single-crystals. In pure Mg poly-crystals, the elliptic indent shape is observed in each grain, and a large deformation occurs in the vicinity of the grain boundary in order to keep bonding two grains at the grain boundary.