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在镍基单晶超合金中,由于单晶Ni的晶格常数比单晶Ni3Al的稍小,在Ni/Ni3Al晶界面 上必然要出现错配.采用分子动力学模拟了镍基单晶超合金的Ni/Ni3Al晶界的结 构,考虑 了两个不同的初始模型,并进行了分子动力学弛豫.弛豫的结果均表明:由于晶格的差异形 成的错配能不是通过长程晶格错配的方式来释放,而是通过在局部区域形成位错的方式释放 的.由于Ni3Al相周围Ni相环境的不同,形成的位错也有所不同.
关键词:
镍基单晶超合金
晶界
分子动力学模拟 相似文献
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The mosaic structure in a Ni-based single-crystal superalloy is simulated by
molecular dynamics using a potential employed in a modified analytic embedded atom
method. From the calculated results we find that a closed three-dimensional misfit
dislocation network, with index of $\langle 011\rangle${\{}100{\}} and the side
length of the mesh 89.6\,{\AA}, is formed around a cuboidal $\gamma '$ precipitate.
Comparing the simulation results of the different mosaic models, we find that the
side length of the mesh only depends on the lattice parameters of the $\gamma $ and
$\gamma '$ phases as well as the $\gamma $/$\gamma '$ interface direction, but is
independent of the size and number of the cuboidal $\gamma '$ precipitate. The
density of dislocations is inversely proportional to the size of the cuboidal
$\gamma '$ precipitate, i.e.~the amount of the dislocation is proportional to the
total area of the $\gamma $/$\gamma '$ interface, which may be used to explain the
relation between the amount of the fine $\gamma '$ particles and the creep rupture
life of the superalloy. In addition, the closed three-dimensional networks assembled
with the misfit dislocations can play a significant role in improving the mechanical
properties of superalloys. 相似文献
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