Grain Boundary Nanohardness of Coarse Grain Alumina.

Here, we present the results of nanoindentation experiments conducted at ultralow peak loads of, for example, 1000, 5000, and 10,000 μN on a dense (~99.5%), coarse grain (~10 μm) alumina ceramic. The results showed that the nanohardness values of alumina were sensitive to the applied loads as well as to the locations of measurements, for example, the center of the grain, away from the center of the grain and at the vicinity of the grain boundary. The location sensitivity of nanohardness was linked to compositional variations of the different locations and to the presence of an amorphous phase. [ABSTRACT FROM AUTHOR]