摘要
采用熔融玻璃净化与循环过热相结合的深过冷技术,研究共晶合金Ni-3.6%B在不同的冷却速率和过冷度下凝固的室温组织变化规律。结果表明,过冷度和冷却速度都对凝固组织形态有重要影响,过冷度从16 K逐渐增加到301 K,熔断后的初生相-αNi由棒状晶转变为粒状晶,共晶组织从层片状转变为非规则点状组织;在大过冷条件下,改变冷却条件,冷却速率由真空炉中空冷、水淬、Ga-In合金淬冷和铜模激冷逐次增加,则所得室温共晶组织形态会由非规则点状转变为规则层片状。进一步理论分析表明,在小过冷条件下,共晶合金Ni-3.6%B的室温组织形态主要由过冷度决定,而在大过冷条件下,共晶组织形态则由冷却速率决定。
Microstructure evolution of Ni-3.6 % B alloy at different undercooling and cooling rates was studied by combination of molten-glass and cyclic superheating. The results show that both undercooling and cooling rate play an important role in evolution of microstructure morphology. When undercooling increased from 16 K to 301 K, the break-up α-Ni dendrites evolved from rod to granular and the eutectic transferred from lamellar to anomalous dot. As the increase of the cooling rate i. e. from nature cooling, water quench, Ga-In quench to Cu mold chilling, a transition of microstructure morphology from anomalous dot to lamellar eutectic was observed. Further theoretical analysis indicates that the microstructure morphology of Ni-3.6% B alloy is controlled by undercooling in small undercooling, whereas, by cooling rate in large undercooling.
出处
《铸造技术》
CAS
北大核心
2010年第4期411-416,共6页
Foundry Technology
基金
国家自然科学基金(50771084)
霍英东青年教师基金(111502)
