大体积Ni-Sn共晶合金的化学净化与过冷

将化学净化引入深过冷研究.采用熔融玻璃净化、循环过热与气氛化学净化结合的方法，使100gNi-Sn共晶合金在慢冷条件下重复实验12次均获得268K的大过冷度.该过冷度可保持30个过热循环周期不衰减气氛化学净化机制是以化学反应抑制合金液与熔融玻璃界面上金属氧化物质点的增加，使过冷熔体的异质形核率稳定，从而使过冷度稳定化学净化的主要控制参数是气氛反应温度.但它在达到某一值后，过冷度的变化不明显

CHEMICAL DENUCLEATION AND UNDERCOOLING OF BULK Ni-Sn EUTECTIC ALLOY

Chemical denucleation is introduced to the study of undercooling. 100g Ni-Sn eutectic alloy is undercooled up to 268K under slow cooling condition by means of combination of melted glass denucleation, cyclical superheating and cooling with atmosphere chemical denucteation. 12 experiments were carried out repeatedly. The maximum undercooling keeps from reduction for 30 cycles. The mechanism of atmospheric chemical denucleation is that, the accumulation of the metallic oxide particles at the interface between melted glass and melted alloy is suppressed, which stabilize the heterogeneous nucleation frequency at the interface so as to stabilize undercooling. The temperature of atmospheric reaction is a main controlling parameter. However, as the temperature of atmospheric reaction exceeds a limitation. undercooling keeps almost unchanged.