Nanocrystalline Ni3Al-based alloys obtained by recycling of aluminium scraps via mechanical alloying and consolidation

Bulk nanocrystalline Ni3Al-based alloys were produced by ball milling of powdered aluminium scrap alloys (two silumines with chemical compositions: Al87.5Si7.8Cu2.1Fe0.7Zn1.4Mn0.4Mg0.1 (R1 scrap) and Al88.4Si5,7Cu3,9Fe0,9Zn0,6Mn0.5 (R2 scrap)) with addition of Ni powder and subsequent hot-pressing consolidation. The final products of mechanical alloying were consolidated at 1000 degrees C for 180 s under the pressure of 7.7 GPa. The powders and the compacted samples were examined by XRD method. The results obtained show that during the milling supersaturated solid solutions Ni(Al, Si ... ) are formed and during the consolidation the disordered solid solutions transform into ordered nanocrystalline Ni3Al intermetallic based phases with a mean crystallite size of similar to 30 nm. The microhardness of the produced Ni3Al-based alloys is 955 for R1 process and 928 HV0.1 for R2 process respectively. The density of the pellets is nearly 100% of theoretical value for the Ni3Al intermetallic phase and the open porosity of the compacts is negligibly small. (C) 2016 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.