Abstract:Ultrasonic arc spray atomization (UASA) method was used to prepare high-melting-point, immiscible AgNi15 (mass fraction, %) composite particles. Sieving was used to determine the size distribution of the AgNi15 particles. The morphology, rapidly solidified structure and metastable solution expansion of the AgNi15 particles were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS), respectively. The results show that the AgNi15 composite particles are spherical and well-dispersed, and the mass fractions of the particles with diameters <74 μm and <55 μm are 99.5% and 98%, respectively. The rapidly solidified structure of the AgNi15 particles consists of spherical nickel-rich b(Ni)-phase particles dispersed throughout a silver-rich a(Ag)-phase matrix and a(Ag)-phase nanoparticles dispersed throughout larger b(Ni)-phase particles. The silver and nickel in the AgNi15 particles form a reciprocally extended metastable solution, and the solid solubility of nickel in the silver matrix at room temperature is in the range of 0.16%-0.36% (mole fraction).

Key words: AgNi15 composite particle; ultrasonic arc spray atomization; rapidly solidified structure; metastable solution extension