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The α variant selection and microstructure evolution in a new metastable β titanium alloy TB17 were studied in depth by DTA, microhardness, XRD, SEM, and EBSD characterization methods. Under the rapid cooling rate conditions (150 °C/min–400 °C/min), only a very small amount of granular αWM (α Widmanstatten precipitates within the grains) precipitated within the grains. The secondary α phase precipitated in the alloy changed from granular to fine needle-like at moderate cooling rates (15 °C/min–20 °C/min). When continuing to slow down the cooling rates (10 °C/min and 1 °C/min), the αGB (α precipitates along the β grain boundaries), αWGB (α Widmanstatten precipitates that developed from β grain boundaries or αGB) and αWM grew rapidly. Moreover, the continuous cooling transformation (CCT) diagram illustrated the effect of cooling rate on the β/α phase transition. EBSD analysis revealed that the variants selection of α near the original β grain boundary is mainly divided into three categories. (i) The double-BOR (Burgers orientation relationship) αWGB colonies within neighboring β grains grow in different directions but have the same crystallographic orientation. (ii) The double-BOR αWGB colonies within neighboring β grains have different growth directions and different crystallographic orientations. (iii) The double-BOR αWGB colonies within the same grain have the same growth direction, but different crystallographic directions. And these double-BOR αWGB colonies correspond to two variants of the given {0001}α//{110}β.

Summary: Autophagy is a conserved biological process that maintains cell homeostasis by targeting macromolecules for lysosome-mediated degradation. The levels of autophagy are relatively lower under normal conditions than under stress conditions (e.g., starvation), as autophagy is usually stimulated after multiple stresses. However, many autophagy-related regulators are still expressed under normal conditions. Although these regulators have been studied deeply in autophagy regulation, the nonautophagic roles of these regulators under normal conditions remain incompletely understood. Here, we found that autophagy-related 5 (ATG5), which is a key regulator of autophagy, regulates c-Myc protein degradation under normal conditions through the ubiquitin-proteasome pathway. We also found that ATG5 binds c-Myc and recruits the E3 ubiquitin-protein ligase FBW7 to promote c-Myc degradation. Moreover, ATG5-mediated degradation of c-Myc limits cell growth under normal conditions and is essential for embryonic stem cell differentiation. Therefore, this study reveals a nonautophagic role of ATG5 in regulating of c-Myc protein degradation.