论文标题
合金对滑动间歇性的影响以及对钛对住宿疲劳的影响
The influence of alloying on slip intermittency and the implications for dwell fatigue in titanium
论文作者
论文摘要
停留的疲劳，钛合金的疲劳寿命降低，由于压力低至60％的收益率而导致的疲劳疲劳已与几种未经及时的喷气发动机故障有关。长期以来，脱位滑移已被观察到是一种间歇性的，规模桥梁的现象，类似于地震中看到的现象，但在纳米级，导致人们猜测，较大的应力爆发可能会促进裂纹的初始开口。在这里，我们使用高能X射线衍射显微镜在Ti-7Al-O合金中观察到这种应力爆发。这表明有序ti_3al降水的有害作用是增加稀有pri <a>的大小<a>和bas <a>与滑移定位相关的滑移爆发。相反，添加痕量O间隙是有益的，可降低BAS <a>滑动爆发的大小，并增加基础和棱镜之间的均匀性<a>滑移之间的均匀性。这进一步的证据表明，在工程钛合金针对停留疲劳时，应避免使用易于基础平面滑移定位的长路径。
Dwell fatigue, the reduction in fatigue life experienced by titanium alloys due to holds at stresses as low as 60% of yield, has been implicated in several uncontained jet engine failures. Dislocation slip has long been observed to be an intermittent, scale-bridging phenomenon, similar to that seen in earthquakes but at the nanoscale, leading to the speculation that large stress bursts might promote the initial opening of a crack. Here we observe such stress bursts at the scale of individual grains in situ, using high energy X-ray diffraction microscopy in Ti-7Al-O alloys. This shows that the detrimental effect of precipitation of ordered Ti_3Al is to increase the magnitude of rare pri<a> and bas<a> slip bursts associated with slip localisation. In contrast, the addition of trace O interstitials is beneficial, reducing the magnitude of bas<a> slip bursts and increasing the homogeneity between basal and prismatic <a> slip. This is further evidence that the formation of long paths for easy basal plane slip localisation should be avoided when engineering titanium alloys against dwell fatigue.
