相界面对双相钛合金层裂孔洞形核的影响

利用一级轻气炮对TC4双相钛合金进行加载, 获得初期的层裂状态, 在加载中采用多普勒激光干涉测速技术对样品自由面粒子速度进行测试。在软回收经过加载的样品之后, 借助于金相显微镜、X射线断层扫描、纳米压痕等检测手段进行多维分析, 探讨了相界面对孔洞形核位置的影响。结果表明, 孔洞绝大部分都在α相内形核, 而不是如准静态损伤理论预测的形核于α/β相界面。这是由于相界面的反射与透射作用, 当冲击波从高阻抗α相传入到低阻抗β相时, 会在α相内产生拉伸脉冲, 当拉伸脉冲足够大时, 导致在α相内产生孔洞。

Effects of Phase Interface on Void Nucleation of Spallation in Dual Phase Titanium Alloy

TC4 dual phase titanium alloy was dynamically loaded by one-stage light gas gun, resulting in an initial spallation state. During the loading, the velocity of free surface particles was measured with photonie Doppler velocimetry (PDV). The effect of α/β phase interface on dynamic damage nucleation, growth, and coalescence in TC4 were investigated by multidimensional testing techniques, such as optical microscopy, X-ray computer tomography and nanoindentation. Results showed that a majority of voids were nucleated within α-phases, rather than at the α/β phase interface as prediction by the quasi-static damage theory. Because of the effects of reflection and transmission of shock wave at the phase interface, a tensile pulse would be formed within α-phase when the shock wave was transmitted from α-phase with high impedance to β-phase with low impedance. And when this tensile pulse was large enough, voids could be formed in α-phase.