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UNDERCOOLING AND HETEROGENEOUS NUCLEATION IN IRON-NIOBIUM AND NICKEL-NIOBIUM ALLOYS

铁铌和镍铌合金中的过冷和异质形核

基本信息

批准号：
15560637
负责人：
MASAYUKI Kudoh
金额：
$ 2.37万
依托单位：
HOKKAIDO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2004
项目状态：
已结题

项目摘要

The effects of heterogeneous substances on undercooling and solidified microstructure were investigated for Iron-niobium and Nickel-niobium binary alloys. An alumina crucible and a crucible covered with commercial glass were used in this experiment. The samples were kept for 1 hr after heating up to 1823K in the Fe-Nb alloy and 1173K in the Ni-Nb alloy and quenched at 1723K and 1673K, respectively, to keep microstructures just after solidification. The experiment on the ternary alloys made by adding 1mass% carbon to the binary alloys was also done. The results obtained are summarized as follows.(1)The undercooling of the Fe-Nb and Ni-Nb alloys increased and reached to 15K at 2mass%Nb and 80K at 1mass%Nb, respectively. The undercooling of both alloys decreases with increasing Nb concentration. The under cooling of the Ni-Nb alloy is always larger than that of the Fe-Nb alloy. (2)When the glass covered crucible was used, the undercooling became larger and it reached to 120K in the case of Ni-Nb alloy. (3)The undercooling of the ternary alloys became lower than those of binary alloy because of carbide formation. The undercooling in the ternary alloys decreased even if glass covered crucible was used. (4)The formation process from dendrite morphology to grain structure was different from the solvent of the alloy. That is, the grain formation in the Ni-base and dendrite formation in the Fe-base alloys are easy to occur. It is concluded that crucible wall mostly acts as heterogeneous materials and subsequently the oxide or carbide formed in the melt also acts as the heterogeneous substances. In addition, the undercooling of the Ni-base alloy was always larger than that of Fe-base alloys because Fe oxide is easy to form compared with Ni oxide.

研究了非均质对铁-铌和镍-铌二元合金过冷度和凝固组织的影响。实验中使用了氧化铝坩埚和覆盖有商业玻璃的坩埚。Fe-Nb合金和Ni-Nb合金分别加热到1823K和1173K后保温1h，并分别在1723K和1673K下淬火，以保持凝固后的组织。并对碳质量分数为1%的三元合金进行了实验研究。主要研究结果如下：(1)Fe-Nb和Ni-Nb合金的过冷度分别在Nb质量分数为2MASS%和1MASS%Nb时达到15K和80K。两种合金的过冷度均随Nb含量的增加而减小。Ni-Nb合金的过冷度总是大于Fe-Nb合金的过冷度。(2)当使用玻璃覆盖的坩埚时，过冷度变大，对于Ni-Nb合金，过冷度达到120K。(3)由于碳化物的形成，三元合金的过冷度低于二元合金。即使使用玻璃覆盖的坩埚，三元合金的过冷度也会降低。(4)从枝晶形态到晶粒组织的形成过程与合金的溶剂不同。也就是说，在镍基合金中容易发生晶化，在铁基合金中容易发生枝晶形成。结果表明，炉壁主要起非均相物质的作用，熔体中形成的氧化物或碳化物也起非均相物质的作用。此外，镍基合金的过冷度始终大于铁基合金，这是因为与镍基合金相比，铁基合金更容易形成氧化物。