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研究了2197-T851合金的疲劳裂纹萌生与扩展特性。结果表明,2197铝锂合金的疲劳裂纹萌生与应力水平有关,在较低应力下,主要萌生在第二相粒子、第二相粒子/基体界面以及表面缺陷处,而在较高应力水平下,还出现沿滑移带和晶界处萌生。裂纹的扩展优先沿有利滑移面,在晶粒间的扩展以沿{111}面的穿晶扩展为主,也有沿小角度晶界扩展的情况,合金具有很好的平面滑移性。裂纹在晶粒内的扩展并非沿一个滑移系的直线扩展而是频繁发生偏折,却始终沿{111}面,可剪切共格相δ’粒子造成晶内扩展路径曲折。
The fatigue crack initiation and propagation properties of 2197-T851 alloy were studied. The results show that the fatigue crack initiation of 2197 Al-Li alloy is related to the stress level. Under low stress, it mainly occurs at the second phase particles, the second phase particles / matrix interface and the surface defects. At higher stress levels, Also appeared along the slip band and grain boundary initiation. The extension of the crack is favorable along the favorable slip plane, and the expansion between the grains is mainly dominated by the transgranular expansion of the {111} plane, and also extends along the small-angle grain boundaries. The alloy has good plane slip properties. The propagation of cracks in the grain does not extend along the straight line of a slip system but occurs frequently. However, along the {111} plane, the particles of the coherent phase δ ’can be sheared to cause a tortuous path in the crystal.