Microstructural characterization of Al-3Ni atomized powder alloy with particle size +45 -88 μm and +106 -180μm

Full text: The powder metallurgy method stands in the development of metallic alloys of high structural refinement and has a great potential for application in compact products with optimization properties. The metallic powder processing by gas atomization promotes a high refinement in the crystalline structure and consequently a good potential for improvement on mechanical properties in consolidated products, also enabling the production of a metallic alloy with distinct components. Aluminum alloys has a particular importance in the industry due its low density and there is a lack of studies investigating the influence of the nickel as an alloy element in the sense that can promote the hardness by the formation of the Al₃Ni phase. The aim of this work is to analyze microstructurally an Al-3Ni atomized powder alloy under two ranges of powder particle size. The Al-3Ni was processed by rapid solidification atomization in a vertical atomizer with inert nitrogen gas, using aluminium and nickel with 99.9 (wt%) purity. From the resulting powder, the two particles size ranges were selected by sieving, obtaining a range of 106μm to 180μm and another of 45μm to 88μm. As the cooling rate is inversely proportional to the particle size and to the average grain size of the aluminium alpha matrix (Al-α phase), both powder was analyzed and compared microstructurally by optical microscope, scanning electron microscopy (SEM) and X-Ray diffraction (XRD), identifying the morphology of the powder particles, the present phases, the distribution and the morphology of the crystalline structure. As expected, the smaller powder particles presented a greater structural refining of the aluminium alpha matrix and a better particle dispersion of the Al3Ni phase. (author)