Development of a nanostructure microstructure in the Al-Ni system using the electrospark deposition process

摘要

Electrospark deposition (ESD) was applied to produce aluminum-nickel coatings consisting of nanostructured Al and Al_3Ni phases. An ESD electrode was manufactured from a hypo-eutectic aluminum-Al_3Ni alloy using chill casting. Line deposition tests were performed to determine the optimal processing parameters resulting in a high quality deposit. X-ray diffraction (XRD) as well as optical and field emission scanning electron microscopy (FE-SEM), were performed to determine the composition and microstructure of the resulting depositions. It was determined that a capacitance of 20μF and a voltage of 100 V resulted in the highest quality deposition. Furthermore it was determined that the ESD process was capable of producing a microstructure consisting of highly refined aluminum and Al_3Ni phases. The grain size of the aluminum phase was calculated, through the application of the Scherrer equation, to be ～25 nm. While, via scanning electron microscopy the grain size of the Al_3Ni phase was determined to be ～44 nm. Also it was determined that multiple deposition passes resulted in increasing the thickness of the deposit, however resulted in decreased deposit quality. Furthermore, it was determined that increasing the energy-density (pulse-energy divided by electrode cross-sectional area) resulted in increasing deposit thickness, until a maximum was obtained using an energy-density of ～0.8J/mm~2. However, increasing the energy-density beyond this point resulted in decreased deposit quality.