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Ti5 0Al存在两类氢脆 ,即氢化物引起的脆性以及原子氢引起的滞后断裂 .室温时TiAl中的氢全部变为氢化物 ,当氢浓度较低时为 (TiAl)Hx;当氢浓度很高时将生成多种氢化物 .随氢化物含量升高 ,KⅠC下降 ,即显示氢化物脆 .表面镀Ni P避免阴极腐蚀后预充氢使氢化物饱和 ,然后加载充氢 ,进入的原子氢通过扩散、富集后能导致滞后断裂 .动态充氢使断裂临界应力强度因子下降约 5 0 % ,其中 2 0 %归因于氢化物 ,而 3 0 %则归因于原子氢 .TiAl氢化物脆的本质和任何第 2相引起的脆性相同 .原子氢引起的滞后断裂则是氢促进局部塑性变形 ,局部应力集中等于被氢降低了的原子键合力 ,从而引起氢致裂纹形核、扩展的结果 .
There are two types of hydrogen embrittlement in Ti5AlAl, namely the hydride-induced brittleness and the delayed fracture caused by atomic hydrogen. The hydrogen in TiAl at room temperature becomes all hydride, and (TiAl) Hx when the hydrogen concentration is low; when the hydrogen concentration is very low High will generate a variety of hydride. With increasing hydride content, KIC decreased, which shows the hydride brittle surface Ni P to avoid pre-charge after the cathodic hydrogenation hydride saturation, and then charged with hydrogen, into the atomic hydrogen After diffusion and enrichment, it can lead to delayed fracture.Dynamic charging of hydrogen reduces the critical stress intensity factor of fracture by about 50%, of which 20% is due to hydride and 30% due to atomic hydrogen.TiAl hydride The brittle nature is the same as the brittleness caused by any phase 2. The delayed fracture caused by atomic hydrogen is that hydrogen promotes local plastic deformation and the local stress concentration is equal to the atomic bonding force reduced by hydrogen and thus leads to hydrogen crack nucleation and expansion Results.