Study On The Undercooling And Solidification Behaviors Of CuTi/CuSn/NiSn Binary Alloys

Cu₈₂Ti₁₈, Ni₂₀Sn₈₀ and Cu₉₅Sn₅ ingots were prepared by remelting and casting in an argon-arc furnace, then solidified by glass fluxing, the effects of sample volume, heat preservation time, superheat temperature and circular times on the undercooling of the sample were researched in the glass fluxing experiment. Their solidification morphology, structural evolution and microhardness were investigated by X-ray diffraction, Metallographic microscope and the Vicker's sclerometerm.X-ray diffraction analysis showed that the diffraction intensity of the sample decreased with the increase of the circular times, and the diffraction intensity of small size alloy was lower than large size alloy in the same glass fluxing condition.Research results exhibited that element Ti can occur chemical reaction with the fluxing B₂O₃ on high temperature,so Cu-Ti alloy cannot be purified by the fluxing B₂O₃. After glass fluxing, the solidification morphology of Ni₂₀Sn₈₀ alloy distributed equably, and grain refine behavior was obvious. The undercooling of small size alloy Cu₉₅Sn₅ became higher with the increase of the circular times, the solidification morphology transformed from coarse dendrites to equiaxed grains and grains refined, microhardness reduced with the increase of circular times. The undercooling of bulk alloy Cu₉₅Sn₅ became higher with the increase of the circular times. Due to the cooling rate difference of the external and internal, their solidification morphology distributed asymmetric, the internal microhardness lowered with the increase of the cooling rate, while the external of the sample occurred the surface hardening behavior.