Estudio de la descomposición de fases durante el sinterizado por plasma de compósitos Al-5%Ni₃Al

The synthesis of Al-matrix composites reinforced with nanocrystalline intermetallic particles of Ni₃Al was carried out with the Spark Plasma Sintering (SPS) technique. The Al-5%Ni₃Al powder mixture was sintered by SPS at two different conditions: (i) 450 °C, 47 MPa and 180 s (4M47) and (ii) 520 °C, 16 MPa and 600 s (5M16). The Ni₃Al particles were obtained by mechanical alloying after a milling time of 1260 ks. The composites show partial decomposition on the Ni₃Al-Al interface, with the formation of the Al₃Ni and Ni₂Al₃ phases. The analysis by TEM confirms the nanometric characteristics of the Ni₃Al particles in the composites. The sintered composites 4M47 and 5M16 presented 95% and 87% of the theoretical density and Vickers microhardness values of 62.3±7 and 55.3±5 HV respectively. Nanoindentation tests show that the mechanical properties of the Al₃Ni, Al₃Ni₂ and Ni₃Al intermetallics are higher in high-pressure sintering conditions.