The microstructures of Ti-6Al-4V following laser processing depend primarily on the phase transformation of β to α, but their development is constrained by the rapidly changing temperature in the small fusion zone. In-situ synchrotron X-ray diffraction was utilized to probe the rapid phase evolution in single melt tracks with high angular and temporal resolution. Both fully martensitic and mixed α+α′+β microstructures were confirmed by microscopy. Cooling rates were inferred from the lattice parameter history and complementary thermal simulation. It was found that the threshold cooling rate for fully martensitic transformation is in the range between 2900 and 6500°C/s.

激光加工后 Ti-6Al-4V 的显微组织主要依赖于 β 到 α 的相变，但它们的发展受到小熔合区温度快速变化的限制。原位同步加速器 X 射线衍射用于探测具有高角度和时间分辨率的单熔体轨迹中的快速相演化。完全马氏体和混合 α+α'+β 显微组织均通过显微镜确认。从晶格参数历史和补充​​热模拟推断冷却速率。发现完全马氏体转变的阈值冷却速率在 2900 和 6500°C/s 之间的范围内。