Studies on the influence of electron beam deflection techniques on the quality and properties of surface alloyed cast Al material with Cu based additive

Abstract

Electron beam alloying (EBA) using a Cu-36Ni additive was examined with the specific aim of improving the hardness and wear behaviour of a cast Al alloy (AlSi10Mg). To this end, investigations were carried out using different beam deflection techniques to identify the correlations between the area of instantaneous energy distribution input and the layer characteristics that resulted, such as surface deformation, layer geometry, hardness gradient and the homogeneity of the alloyed microstructure. The average hardness of the EBA layers was defined varied in the range of from 200 to 700HV0.5 by adjusting the energy input and the alloyed content respectively. Detailed investigations of the EBA layer microstructures using EDX and XRD analyses detected α-Al, primary Si and a number of intermetallic phases. The higher the content of intermetallic phases, the higher was the layer hardness.The wear behaviour under abrasive test conditions was studied by scratch testing with a constant load of 20N, and under adhesive conditions by unlubricated pin-on-disc testing with a normal load of 20N over a sliding distance of 50m.EBA layers with an average hardness of approx. 400HV0.5 delivered the best results with respect to both the layer quality generated (phase distribution, cracks and pores) and the resulting wear behaviour.