Re对镍基合金晶格错配度的影响

Effects of Re on lattice misfit of nickel-based superalloys

通过对不同Re含量镍基合金进行室温、高温X射线衍射谱线测定及持久性能测定,研究了Re含量及温度对镍基合金中γ、γ′两相晶格错配度及持久寿命的影响规律.结果表明:随Re含量增加,合金中γ、γ′两相的晶格常数增大,两相界面的晶格错配度及错配应力减小,致使蠕变期间合金中γ′相的筏形化速率降低,并可较大幅度地提高合金在高温区间的持久寿命.与γ′有序相比较,无序的γ相原子结合力较弱,且热容较大,致使其有较大的膨胀系数,故随温度提高,合金中两相的晶格错配度绝对值增大.合金中γ、γ′两相的晶格常数、热膨胀系数随温度变化服从指数规律;在试验的温度范围内,提出的数学表达式在高温区间,可较好地模拟γ、γ′两相的膨胀特性.

By means of X -ray diffraction analysis at different temperatures, an investigation has been made into the influences of Re and temperature on the lattice misfit and stress rupture properties of nickel based superalloys. Results show that the lattice parameters of γ and y phases in the alloys increase and the lattice misfit between y/y phases decrease with the increase of the Re content, which decreases the rafted rate of the γ phase and enhance the stress rupture lifetimes of the superalloy during high temperature creep. Compared to the ordered γ phase, the disordered y phase possesses a higher expansion coefficient, which is attributed to the weaker binding force between the atoms and higher thermal capacity, in the one. Therefore, the lattice parameters and misfit value of γ and y phases in the alloy increase veith temperature. The dependence of the lattice parameters and expansion coefficients of γ and γ phases on temperature obeys the exponential regularity. An expression is put forward in the range of the applied temperatures, which may primely simulate the expansion characteristic of the γ and y phases in the alloy m the high temperature range.