An alternative method for continuous property measurement during depth-sensing indentation.
Based on the Oliver-Pharr framework, we propose an iteration scheme to continuously evaluate the hardness during monotonic loading in nanoindentation. The new method has been applied to measure the hardness of various crystalline materials including Al, Cu, Ni3Al(Cr,B) and MgO, where an obvious indentation size effect (ISE) has been characterized. The results on MgO measured using the new method show excellent agreement with those from the more conventional, dynamic Continuous Stiffness Measurement (CSM) method. In a-Se and PP, an apparent ISE was observed when constant-rate loading schedules were used. However, no ISE was observed in these two materials when using exponential loading schemes which corresponded to constant strain rates. The apparent ISE under constant-rate loading was thus very likely the result of the strong strain-rate dependence of the flow resistance in these two materials. The new method therefore produced the correct ISE behaviours in various materials under different loading situations.
|Main Author:||Chiu, Y.|
|Other Authors:||Feng, G., Tang, B., Ngan, A.|