An analysis of load-depth data in depth-sensing microindentation experiments for intermetallic MgB2

The dynamic microindentation experimental technique was used to characterize the mechanical properties of intermetallic MgB2. The indentation load-displacement curves of the sample were obtained under different levels of peak loads. The widely adopted Oliver-Pharr method was used to analyze the unloading segments of these curves. It was found that both the hardness (H) and the reduced (elastic) modulus (E(r)), exhibit significant peak load dependence (i.e., indentation size effect (ISE)). On the other hand, h(f)/h(max) values were used to clarify the indentation deformation behavior of the intermetallic MgB2 sample. The averages of experimental h(f)/h(max) values were lower than the reported critical value (0.7) for each measurement. This result implies that MgB2 specimens show work hardening behavior.