کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1578888 | 1001216 | 2011 | 6 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Creep mechanisms of U720Li disc superalloy at intermediate temperature Creep mechanisms of U720Li disc superalloy at intermediate temperature](/preview/png/1578888.png)
The microstructures of U720Li disc superalloy have been investigated by transmission electron microscopy (TEM) before and after creep test at 725 °C/630 MPa. The evolution of the crept microstructures was marked as three different stages (I, II and III) corresponding to gradually increased strain 0.1%, 5% and 27%, respectively. At stage I, dislocations bypassed secondary γ′ via Orowan loops. At stage II, partial dislocations started to shear secondary γ′, leaving stacking fault (SF) behind and microtwins formed in part of grains. At stage III, grain boundary sliding occurred due to very large strain and increased effective stress. The results indicated that the creep mechanisms of U720Li at 725 °C/630 MPa evolved with gradually increased strain. Orowan looping process combining dislocation slip and climb and partial dislocations shearing precipitates were the main creep mechanisms. It is suggested that decreasing the interparticle spacing of secondary γ′, strengthening secondary γ′ and decreasing stacking fault energy (SFE) of γ matrix may be effective methods to improve the creep property at relatively higher temperatures.
► Crept microstructures of U720Li at 725 °C/630 MPa have been investigated by TEM.
► Orowan looping process combining dislocation slip and climb and partial dislocations shearing precipitates were the main creep mechanisms.
► Grain boundary sliding occurred at last creep stage.
► Three methods were suggested to improve the creep property at relatively high temperature.
Journal: Materials Science and Engineering: A - Volume 528, Issue 15, 15 June 2011, Pages 5106–5111