Using the ratio: maximum load over unload stiffness squared, Pm/Su², on the evaluation of machine stiffness and area function of blunt indenters on depth-sensing indentation equipment

Materials Research

Juan Manuel Meza²  María Cristina Moré Farias¹  Roberto Martinz De Souza¹  Luis Javier Cruz Riaño¹ 

[1] ,Pontifical Bolivarian University New Materials Research Group Medellín Antioquia ,Colombia

关键词: depth-sensing indentation;    nanoindentation;    mechanical properties;    machine compliance;    tip roundness;   

DOI  :  10.1590/S1516-14392007000400019

来源: SciELO

【 摘 要 】

Depth sensing indentation study was conducted in a Fischerscope H100V machine, equipped with a Vickers indenter with a tip roundness of approximately 1330 nm. Tests were carried out on soda-lime glass, fused silica, sapphire, aluminum (1100 alloy), high alloyed steel, titanium and copper. The widely used iterative method of Oliver and Pharr was unsuccessful in the attempts to analyze machine compliance and indenter area function. Therefore, an alternative procedure was adopted. The alternative procedure is based on the ratio between maximum load and unload stiffness squared, Pm/Su². It was found that this procedure, which is not iterative, gives good results. A careful study of the Pm/Su² ratio, lead us to conclude that the Fischercope machine has a low compliance which depends on the sample mounting. This low compliance in conjunction with the recent discovery of the dependence of beta factor on the tip roundness/maximum depth ratio, which appears in the relation between contact stiffness and contact area, explains why the iterative method does not converge. However, variations in beta and machine compliance produces deviation on the hardness and elastic modulus lower that 6% with respect to expected values for the materials and the machine studied in this work.

【 授权许可】

CC BY   
 All the contents of this journal, except where otherwise noted, is licensed under a Creative Commons Attribution License