Laser-induced formation of conical bumps on the surface of superrefractory metals

Пестов Ю.И., Макин В.С. Лазерно-индуцированное формирование конусообразных выступов на поверхности сверхтугоплавких металлов // Оптический журнал. 2008. Т. 75. № 6. С. 34–42.

Pestov Yu.I., Makin V.S. Laser-induced formation of conical bumps on the surface of superrefractory metals [in Russian] // Opticheskii Zhurnal. 2008. V. 75. № 6. P. 34–42.

Yu. I. Pestov and V. S. Makin, "Laser-induced formation of conical bumps on the surface of superrefractory metals," Journal of Optical Technology. 75 (6), 371-377 (2008). https://doi.org/10.1364/JOT.75.000371

The formation of conical bumps on W, Ta, and Mo surfaces as a result of irradiating them with a laser pulse in an atmosphere of air, nitrogen, or helium and in vacuum have been experimentally studied at an irradiation-energy density above the melting threshold but below the blowout threshold of the melt from the irradiation zone by vapor pressure. A strong dependence of the bump height on the composition of the gaseous atmosphere is detected. The minimum radius of curvature of the tip of 0.5μm and a tip angle of the conical bump of 60° were observed on molybdenum for a bump height of 19μm above the original surface level. It is shown that the regularities of formation of the conical bumps on the metals are associated with the final contact angle of wetting of the solid phase by its melt and with the dependence of the contact angle on the composition and chemical activity of the atmosphere. A model has been constructed of the formation of a conical bump during the crystallization of a limited bath of the melt.