摘要
目的:研究温度对液态铋(Bi)结构的影响,初步探讨纯元素液态结构对合金凝固组织的影响。方法:通过液态纯Bi结构的X射线衍射分析,得到300~900℃温度范围内液态Bi的结构因子、偶分布函数、径向分布函数,计算不同温度下的配位数、原子团簇尺寸、有序度参量、双体相关熵等。凝固试验是把纯Cu加入到结构变化前、后的Bi熔体,制备了Bi-2wt%Cu合金,试样经打磨、抛光后运用4%硝酸酒精溶液进行腐蚀,运用扫描电子显微镜观察合金微观形貌特征。结果:在300℃和475℃的结构因子曲线第一峰右侧均存在一个明显的肩膀。当温度高于700℃时,结构因子和偶分布函数的第一峰高度、原子团簇尺寸、有序度参量随温度升高而急剧下降;而双体相关熵则突然增加。凝固试验表明结构未改变的Bi熔体凝固后的Cu相呈方块状;而结构改变的Bi熔体凝固所得的Cu相呈树枝状。结论:Bi的液体结构在700~762℃范围内发生了重组,温度诱导Bi熔体结构转变具备有序-无序转变特征。Bi熔体的结构变化可用于调控Bi-2wt%Cu合金的熔体状态,进而改变其凝固组织。该研究有望为探索研究新的过热处理技术,进一步深化液态遗传效应的研究深度和广度提供参考。
Objective：To explore the effect of temperature on the structure of liquid bismuth（Bi）,and preli minarily investigated the relation of liquid structure of pure element with the solidified microstructure of alloy.Methods：Based on the analysis of the X-ray diffraction data of liquid Bi,the structural factors,pair correction function and radial distribution function of liquid Bi were obtained within the temperature range from 300 to 900 ℃,and moreover the coordination numbers,the size of short-range orders,the orderingdegree decreased and the pair correlation entropy were calculated at different temperatures.The solidification experiment was that the Bi-2 wt% Cu alloys were prepared by the addition of copper to the structural changed and unchanged melts,respectively.The solidified samples were polished and etched by 4% nitric acid alcohol solution.The scanning electron microscope were used to examine the samples.Results：The obvious shoulder existed at the right of the first peak of structure factors at 300 ℃ and 475 ℃,respectively.When the temperature was higher than 700 ℃,the height of the first peak of structural factors and pair distribution function,correlation radius,order parameter abruptly decreased with temperature increasing,however the pair correlation entropy abruptly increased.The results of solidification experiment showed that the copper phase was blocky in the structural unchanged sample,while was dendritic in the structural changed sample.Conclusion：The structure of liquid Bi recombined in the range of 700-762 ℃.The temperature induced structural change characterized with the transition from order to disorder.the structural change of liquid Bi can be used to control the solidified structure of Bi-2 wt% Cu.This exploration can be helpful to develop new superheated technologies and expand the depth and scope of knowledge on the heredity of liquid.
作者
丁国华
DING Guohua(School of Mechanical and Vehicular Engineering,Bengbu University,Bengbu 233030,China)
出处
《安徽科技学院学报》
2018年第3期63-69,共7页
Journal of Anhui Science and Technology University
基金
国家自然科学基金项目(51101067)
安徽省高校优秀青年人才支持计划项目(gxyqZD2018084)
关键词
液体结构转变
铋
凝固
温度诱导
Liquid structural transition
Bismuth
Solidification
Temperature induction
