铸造TiAl合金凝固组织的截面尺寸效应  

Sectional Dimension Effect of Solidification Microstructure for Cast TiAl Alloy

作　　者：胡海涛[1] 张熹雯[1] 朱春雷[1] 李胜[1] 张继[1] Hu Haitao Zhang Xiwen Zhu Chunlei Li Sheng Zhang Ji(Belling Key Laborary of Advanced High Temperature Materials, Central Iron and Steel Research Institute, Belling 100081, China)

机构地区：[1]钢铁研究总院高温合金新材料北京市重点实验室,北京100081

出　　处：《稀有金属》2017年第7期751-758,共8页Chinese Journal of Rare Metals

基　　金：国家重点基础研究发展计划项目(2011CB605503)资助

摘　　要：采用数值计算和试验的方法,研究了直径30~50 mm Ti Al合金铸锭凝固组织的截面尺寸效应。结果表明:受径向散热和轴向散热竞争的影响,Ti Al合金铸锭的宏观组织存在竞争生长区、径向生长区和冒口影响区,随铸锭高径比增大,竞争生长区和冒口影响区占比减小,径向生长区占比增大。在径向生长区内,对于同一Ti Al合金铸锭,随散热距离的增加,柱状晶宽度增大,但增大的幅度逐渐减小;对于不同直径的Ti Al合金铸锭,在相同散热距离处,较大直径铸锭的柱状晶宽度更宽,且不同直径铸锭柱状晶宽度的差值随径向散热距离的增加而增大。通过拟合径向温度梯度和轴向温度梯度与铸锭直径和轴向散热距离的关系,建立了柱状晶生长方向与铸锭直径和轴向散热距离的关系。通过拟合温度梯度和凝固速率与铸锭直径和径向散热距离的关系,并耦合柱状晶宽度与温度梯度和凝固速率的关系,建立了柱状晶宽度与铸锭直径和径向散热距离的关系。Numerical calculation and experiment were used to study the dimensions size effect of solidification microstructure of TiA1 ingots with diameter from 30 to 50 ram, The results indicated that affected by the cooling competition from radial direction and axial di- rection, the macrostructure of TiA1 ingot included competitive growth zone, radial growth zone and riser affected zone. With the in- crease of height to diameter ratio, the proportion of competitive growth zone and riser affected zone reduced, while the proportion of ra- dial growth zone added. In the radial growth zone, for the same TiA1 ingot, with the addition of cooling distance, the columnar grain width increased, while the increasing extent reduced gradually. For TiA1 ingots with different diameters, there was wider columnar grain in larger diameter ingot at the same cooling distance. And with the extension of cooling distance, the difference of columnar grain width among different diameter ingots gradually expanded. By fitting the relationship of radial temperature gradient and axial te,upera- ture gradient with ingot diameter and axial cooling distance, a quantitative relationship of columnar grain growth direction with ingot di- ameter and axial cooling distance was established. By fitting the relationship of temperature gradient and solidification rate with ingot diameter and radial cooling distance, and coupling the relationship of columnar grain width with temperature gradient and solidification rate, the relationship of columnar grain width with ingot diameter and radial cooling distance was established.

关 键 词：铸造TIAL合金 尺寸效应 柱状晶生长方向 柱状晶宽度 

分 类 号：TG146[一般工业技术—材料科学与工程]