CHARACTERIZATION OF Al-Ni COMPOSITES PRODUCED BY ULTRASONIC POWDER CONSOLIDATION

摘要

Reactive composites, applicable to localized heating applications, were produced from Al and Ni powders by ultrasonic powder consolidation (UPC) at temperatures < 573 K in 1 s. The composites exhibited a fully dense microstructure consisting of a metallurgically bonded Al matrix and nearly undeformed Ni particles distributed in the Al matrix. No indications of reactions were noted between the elements. Differential scanning calorimetry (DSC) revealed two exothermic and one endothermic peaks. The phase evolution during DSC was investigated by X-ray diffraction (XRD). The first exothermic peak initiated at 830 K was due to solid-state formation of Al_3Ni and Al_3Ni_2. At 913 K, an endothermic peak formed due to eutectic melting of Al_3Ni and Al which triggered ignition, producing the second exothermic peak at 925 K. The final reacted materials consisted of Al_3Ni, Al_3Ni_2, AlNi and Ni.