Nanoindentation Testing of the Microstructure of AZ91 Alloy Castings with a WCCoCr Coating

Abstract

The paper presents the results of nanoindentation testing of AZ91 magnesium alloy and a WCCoCr coating deposited by Air Plasma Spraying (APS). In order to determine the material properties of individual components of the microstructure of the AZ91 alloy and the WCCoCr coating, i.e., Vickers hardness – HVIT, indentation hardness – HIT, and indentation modulus - EIT, nanoindentation testing of the individual microstructural components of the AZ91 alloy and the WCCoCr coating was performed. The analysis showed significant differences in material property values between the α-Mg matrix, the γ-Mg17(Al,Zn)12 intermetallic phase, the β(α+γ) eutectic, and the WCCoCr coating. The highest values of indentation hardness and indentation modulus were found in the case of the microstructure (grains) of the WCCoCr coating. The obtained results indicate that the application of the WCCoCr coating significantly improves the tribological properties of the surface layer of AZ91 alloy castings, especially scratch resistance. The results of these tests complement the previously performed scratch tests of the WCCoCr coating.