Surface tension of substantially undercooled liquid Ti–Al alloy

Abstract

It is usually difficult to undercool Ti–Al alloys on account of their high reactivity in the liquid state. This results in a serious scarcity of information on their thermophysical properties in the metastable state. Here, we report on the surface tension of a liquid Ti–Al alloy under high undercooling condition. By using the electromagnetic levitation technique, a maximum undercooling of 324 K (0.19 T _L) was achieved for liquid Ti-51 at.% Al alloy. The surface tension of this alloy, which was determined over a broad temperature range 1429–2040 K, increases linearly with the enhancement of undercooling. The experimental value of the surface tension at the liquidus temperature of 1753 K is 1.094 N m⁻¹ and its temperature coefficient is −1.422 × 10⁻⁴ N m⁻¹ K⁻¹. The viscosity, solute diffusion coefficient and Marangoni number of this liquid Ti–Al alloy are also derived from the measured surface tension.

Keywords:

• liquid metal and alloy
• surface tension
• undercooling

Acknowledgements

The authors are grateful to Mr B.C. Luo, Mr D.L. Geng and Mr L. Hu for their help with the experiments. This work was financially supported by National Natural Science Foundation of China (Grant Nos. 50971103 and 50971105), the Program for New Century Excellent Talents in University and NPU Excellent Personnel Supporting Project of Aoxiang Star.