摘要
采用熔融玻璃与循环过热相结合方法使Fe-80at%Ni合金熔体获得了340K的大过冷,对Fe-80at%Ni过包晶合金在宽过冷范围内凝固组织进行研究。结果表明:在小过冷范围(ΔT<28K),凝固组织为普通树枝晶;当28K<△T<54K时,凝固组织为不规则粒状晶;当54K<△T<70K时,凝固组织为树枝晶;当70K<△T<210K时,凝固组织转变为细小的粒状晶;当△T>210K时,凝固组织为粗大的晶粒。随着过冷度的增加,凝固组织发生了两次粒化和一次粗化过程,分别为由小过冷树枝晶向第一类粒状晶的转变,由大过冷树枝晶向第二类粒状晶的转变和由细小粒状晶向粗大晶粒转变。粒化机理分别是枝晶重熔,枝晶碎断+再结晶和极大的表面能导致小晶粒合并。
The maximum undercooling 340 K was achieved in Fe-80at% Ni melts by using glass fluxing and cycle superheating technique, and solidification structures of undercooled Fe-80at% Ni melts were systematically investigated in a wide undercooling range. The results showed that when the undercooling is less than 28 K, the solidification structures are the common dendrites; when the undercooling goes up into the range from 28 K to 54 K, the structures turn into irregularity granular grains; with the increase of undercooling into the range from 54 K to 70 K, the structures turn into the dendrites again; when the undercooling goes up into the range from 70 K to 210 K, the dendrites break up and regular granular grains form again; when the undercooling is above 210 K, the structures turn into coarse grains. With the increase of undercooling, the solidification structures undergo granulations twice and once coarsening. The first is that dendrites at smaller undercoolings turnes into the first granular grains, the second is that dendrites at higher undercoolings turns to the second granular grains and the third is that second granular grains turns to coarser grains. The first granulation mechanism is dendrite remelting, the second is dendrite breaking-up and recrystallizing, and the third is high surface energy which leads to merging of the little grains into coarser grains.
出处
《铸造技术》
CAS
北大核心
2007年第6期771-774,共4页
Foundry Technology
基金
陕西省自然科学基金(2004E108)
关键词
深过冷
Fe-80at%Ni
凝固组织
粒化机理
High undercooling
Fe-80at % Ni
Solidification structures
Granulation mechanism
