高速撞击Ti44Ni47Nb9合金相变行为及力学性能研究

Phase transformation and mechanical properties of Ti44Ni47Nb9 alloy after high-velocity impact

摘要:

本文针对TiNi基合金在空间使役环境可靠性评价的迫切需求，开展高速撞击TiNi基合金马氏体相变、微观组织结构及力学性能研究。采用火药炮对Ti44Ni47Nb9进行高速撞击，撞击速度为1020 m/s，并对高速撞击后Ti44Ni47Nb9合金三个不同方向的结构与性能进行测试。实验结果表明，沿撞击方向没有发生相变，与撞击方向呈45°和垂直于撞击方向的相变峰均向低温区偏移。弹坑底部以及侧壁出现大量裂纹，在TiNi基体中发现马氏体板条，同时在β-Nb粒子和TiNi基体中观察到大量位错。弹坑附近的硬度最高，随着与弹坑距离的增加，硬度降低，这可能是由于加工硬化及撞击能量分布不均匀而引起的。

Abstract:

Aiming at the urgent demand for reliability assessment of TiNi based alloy working in space, Ti44Ni47Nb9 alloy is impacted at 1020 m/s using a powder gun. Phase transformation, microstructure and mechanical properties in Ti44Ni47Nb9 alloy induced by impact are investigated. The results show that no intermediate phase is formed along the impact direction, the phase transformation temperature shifts to a lower temperature along 45° and vertical to the impact direction of impacted Ti44Ni47Nb9 alloy. A large number of cracks appear at the bottom of the crater and walls, there are martensite plates in TiNi matrix, and many dislocations exist in the β-Nb particles and TiNi matrix. The microhardness reduces gradually with the increase in distance from the crate, this is attributed to working hardening and uneven energy distribution caused by high-velocity impact.