Fig. 5: Bubble escape from the melt pool and entrapment by the solidification front.

a Motion track and velocity of a bubble escape following Marangoni flow. The velocity value is shown in the parula colourmap. The time is shown in the jet colourmap. See the video in Supplementary Movie 6. b Accumulative number of bubble escape, coalesce and are entrapped with increasing time, and it is fitted linearly. Entrapped bubbles are shown in the inset figure. c The rates of bubble escaped and entrapped in a traverse speed of 1 mm s⁻¹, layer 1; 2 mm s⁻¹, layer 1; 1 mm s⁻¹, layer 3; 2 mm s⁻¹, layer 3, respectively. Error bars represent standard deviation. d Accumulative number of bubble escape in total, front and back of melt pool. In (a, b, d), the laser power is 160 W and the traverse speed is 1 mm s⁻¹, layer 3. Scale bars in (a, b) are 300 μm.