Nb和Al对γ-TiAl基合金高温强度的影响

Effects of Al and Nb on high temperature strength of γ-TiAl based alloys

研究了Nb对γ TiAl基合金性能的影响 ,结果表明 ,高Nb合金化能大大提高γ TiAl基合金的高温强度 ,合金含Nb量越高 ,强度就越高。TEM观察表明 ,Nb对γ TiAl性能的影响类似于氧元素 ,增强d—d键的方向性 ,增加普通位错的P N力 ,提高普通位错开动的临界分切应力和滑移阻力。Al对γ TiAl合金性能的影响是通过影响合金中的α2 相含量来影响其性能的。随合金中Al含量升高 ,α2 相含量减少 ,位错运动非热激活阻力降低 ,合金的强度下降。

It is shown from the effect of Nb on γ TiAl based alloys that high Nb content can improve the high temperature yield strength greatly, the higher the content of Nb in TiAl based alloys, the better the strength. TEM analysis shows that the high Nb solution in γ phases can enhance the directionality of d—d bonds and therefore enhance the P N stresses so as to increase the CRSS for ordinary dislocation slip, leading to a higher lattice frictional resistance. The aluminium content has a significant effect on the high temperature yield strength of TiAl based alloys as a result of the changed α 2 content. The athermal activating stress of dislocation slip decreases as Al content increases which results in the decrease of the α 2 content, and the high temperature strength of TiAl based alloys decreases.