Microstructure and Mechanical Properties of Al-Ni Alloys Added Zr and/or Sc Subjected to Equal Channel Angular Pressing

Aluminium-nickel alloys (Al-Ni) are of interest in high-temperature applications due to the high thermal stability of Al3Ni fibers. The mechanical properties of Al-Ni alloys can also be improved in various ways, such as through alloy development with an addition of scandium and zirconium, as well as grain refinement. In this work, the characterization of the microstructure and mechanical properties of Al-Ni alloys with an addition of Zr and/or Sc processed by equal channel angular pressing (ECAP) for 0 and 4 passes at room temperature, was investigated. The microstructure of as-cast, aged, ECAPed, and post-heat-treated specimens was analyzed using optical microscopy (OM) and scanning electron microscopy (SEM) with energy dispersive spectrometry technique (EDS) and electron backscatter diffraction technique (EBSD). The mechanical properties of all specimens were analyzed using the Vickers hardness test. From the experimental results, it was found that the ECAP process increased the structural homogeneity of the α-Al/Al3Ni phase. Additionally, Al3Sc and Al3(Sc,Zr) precipitates effectively improved the hardness of Al-Ni alloys and enhanced the thermal stability of Al-Ni alloys for up to 120 minutes at 300°C.