多层梯度超细晶粒钛的变形机制

Deformation mechanism of multilayer gradient ultrafine grained titanium

采用冷轧与表面机械磨损处理相结合的方法,设计和制备了具有多层梯度化结构的超细晶粒钛。对制备的超细晶粒钛进行力学性能试验,用扫描电子显微镜观察其显微组织形貌,利用透射电镜对材料的变形机制进行了详细研究。结果表明:每一层都有其特定的变形和破坏机制,变形机制包括非晶纳米晶混合层的大量剪切带化、纳米晶粒层的晶界诱导变形和超细晶粒的局部剪切;层与层之间连接处的梯度降低了界面破坏程度、增加了止裂效应,以及提高了接触承载能力;这种复杂的塑性变形提高了多层梯度钛的强度和加工硬化性能。

Ultrafine grained titanium with multilayer and gradient structure was designed and prepared by combining cold rolling and surface mechanical wear treatment.The mechanical properties of the prepared ultrafine grained titanium were tested.The microstructure was observed by scanning electron microscopy,and the deformation mechanism of the material was studied in detail by transmission electron microscopy.The results show that each layer had its own specific deformation and failure mechanism.The deformation mechanism included a large number of shear banding of amorphous nanocrystalline mixed layer,grain boundary induced deformation of nanocrystalline layer and local shear of ultrafine grain core.The gradient at the connection between layers reduced the degree of interface damage,increased the crack arrest effect,and improved the contact bearing capacity.This complex plastic deformation improved the strength and work hardening properties of multilayer gradient titanium.