铸造TiAl合金的凝固偏析特征

Solidification Segregation Characteristics of Cast TiAl Alloy

采用扫描电镜背散射模式和电子探针成分分析研究了TiAl合金铸锭的凝固偏析特征。结果表明,沿柱状晶生长方向合金元素不存在宏观偏析。TiAl合金铸锭的微观偏析按照衬度差别可分为三个区域,呈网状分布的暗灰色区域,以及网格中间的灰色和灰白色区域,其中灰白色区域呈现枝干分布特点。合金元素Ti和V在灰白色区域的含量最高,暗灰色区域的含量最低。Al在暗灰色区域的含量最高,灰白色区域的含量最低。Cr在暗灰色区域的含量最高,灰色区域的含量最低。平行柱状晶生长方向和垂直柱状晶生长方向合金元素的微观偏析特征没有差别,柱状晶内和柱状晶界附近合金元素的微观偏析特征也没有差别。

The solidification segregation characteristics of TiAl alloy ingots were studied by scanning electron microscopy backscatter mode and electron probe composition analysis. The results show that there is no macro-segregation of alloying elements along the columnar growth direction. The micro-segregation of TiAl alloy ingots can be divided into three regions according to the difference of contrast: dark gray areas distributed in the form of a network, and gray and grayish white areas in the middle of the grid. The grayish white areas show the characteristics of branch distribution. The alloying elements Ti and V have the highest content in the grayish white region and the lowest content in the dark gray region. Al has the highest content in the dark gray area and the lowest content in the grayish white area. Cr has the highest content in the dark gray area and the lowest content in the gray area. There is no difference in the micro-segregation characteristics of the alloying elements at the direction parallel to columnar crystal growth orperpendicular to columnar crystal growth, and there is also no difference inside the columnar crystal ornear the columnar boundaries.