含铒近α型高温钛合金中α相的动/静态球化机制

Dynamic and Static Spherical Mechanisms ofαPhase in NearαTitanium Alloy with Erbium

本工作围绕近α型高温钛合金α相球化过程涉及的科学问题开展研究,以探索出具有随机取向的α相组织模式的调控机理。以含铒高温钛合金为研究对象,多尺度研究阐明α相在热、力耦合条件下的组织演化规律,揭示动、静态球化所制备的含铒高温钛合金的组织模式,提炼出近α型高温钛合金α相动/静态球化机制。研究表明,在热力耦合条件下,αp的球化机制由渐进式取向差所控制的动态再结晶机制主导;在单纯热的作用下,αp相的静态球化由扩散控制的β插入模型主导,都会形成取向随机分布的等轴αp相。在880℃、0.001 s^(-1)热力协同变形过程中,变形初期以位错的激发及其与界面的交互作用为主,所激发的滑移位错的伯氏矢量为1/3[2112],形成位错界面等亚结构;随着应变的增大,晶粒间取向差增大,形成完全动态再结晶组织。静态球化后,组织为等轴αp晶粒和β转变组织并存的组织模式。β转变组织中存在β相和二次αs板条,且二次αs板条的宽度在30 nm左右。

The scientific issue was investigated for the spherical mechanisms ofαphase in nearαtitanium alloy with erbium,aimed to preparate theαphase with random crystal orientation.A novel high temperature titanium alloy with erbium was studied to clarify the micro-structural evolution on the thermal mechanical conditions.Meanwhile,the micro-structure model was established to clarify the dynamic and static spherical mechanisms ofαphase.During the thermal-mechanical deformation,the spherical mechanism of lamellarαcolony was the continuous dynamic recrystallization,controlled by the mechanical rotation of the sub-grain followed by dislocation climbing and annihilation by diffusion.During the thermal process,the static spheroidization was developed on basics of theβinserted model.During the thermal-mechanical deformation,the sub-structure was induced by the interaction between the slipping dislocation with b of 1/3[2112].And then,the mis-orientation was increased to develop to the dynamic recrystallization.During the thermal process,the static spherical process,the equiaxialαp grains and retainedβtransformed microstructures were prepared.Furthermore,retainedβtransformed microstructures consisted ofβphase and secondaryαs lamellar with the thickness of 30 nm.