动高压加载条件下Ti-6Al-4V和Ti-47Nb合金层裂微结构特征与断裂机理

Spall Microstructure Characteristics and Fracture Mechanism of Ti-6Al-4V and Ti-47Nb Alloys under Dynamic High-pressure Loading

利用平板撞击实验和样品软回收技术,结合光学显微镜(OM)、扫描电子显微镜(SEM)等微观分析手段,研究了动高压加载条件下Ti-6Al-4V和Ti-47Nb 2种不同类型钛合金的层裂微结构特征与断裂机理。结果表明:Ti-6Al-4V合金的抗层裂破坏能力强于Ti-47Nb合金,其原因在于Ti-6Al-4V合金的高强度。Ti-6Al-4V合金层裂微孔洞大多在α/β两相界面处形核并沿相界扩展,而Ti-47Nb合金中的微裂纹是通过微孔洞直接连通形成。随后汇合的大空洞或大裂纹间形成的绝热剪切带(ASB)加速了试样层裂破坏的产生,Ti-6Al-4V与Ti-47Nb合金均表现出了韧性断裂特征。

Spall microstructure characteristics and fracture mechanism of Ti-6Al-4V and Ti-47Nb alloys were studied by plate impact experiments and＂sample soft-capture＂technology under the dynamic high-pressure loading,as well as microscopic analyses using optical microscopy and scanning electronic microscopy.The results indicate that Ti-6Al-4V alloy has stronger ability of spall resistance than Ti-47Nb alloy because of the high strength of Ti-6Al-4V alloys.The micro-voids in the spalled Ti-6Al-4V alloy almost nucleate at theα/βphase boundaries and propagate along the phase boundaries,and the micro-cracks of Ti-47Nb alloy are directly connected through micro-voids.Subsequently,the adiabatic shear band（ASB）,which forms between macroscopic voids or main cracks,promotes the spall fracture of samples.Ti-6Al-4V and Ti-47Nb alloys fracture with ductile characteristics.