Aluminum-based metal-matrix composites are desirable for the automotive and aerospace industry due to their high mechanical properties, thermal stability, and strength-to-density ratio [1,2]. However, despite these aspects, the wetting properties are essential to characterize the reaction behavior in the liquid-state processing of composites because this knowledge can allow for obtaining even more strengthened materials [3].

In this study, high-temperature experiments were carried out using the sessile drop method to determine the interaction of liquid Al in contact with two different compressed substrates: (i) graphite (Al/Cgr) and (ii) titanium (Al/Ti). The tests were done under a high vacuum atmosphere at isothermal conditions (800°C). During measurements, the capillary purification procedure combined with the non-contact heating was used to eliminate the effect of the native oxide film on an Al drop and the heating history of Al/substrate couples [4-5]. The Al sample was placed in an alumina capillary over the substrate for this. Once the test temperature was reached, the Al drop was mechanically squeezed from the capillary and deposited on the substrate. During high-temperature experiments, the images of the Al/C and Al/Ti couples were recorded by two high-speed monochromatic CCD cameras with a speed of 57 fps from two observation directions. These images were used to calculate the contact angle values between the liquid metal and the investigated substrates.

Under the conditions of this study, the liquid Al exhibited non-wetting behavior (the contact angle Θ>90°) and no permanent bonding between liquid Al and the graphite substrate. In contrast, to the Al/Cgr couple, the liquid Al wets Ti substrate in a short time (Θ<90°). The obtained results are discussed concerning the role of the primary and secondary oxide films on Ti and C substrates on the wetting and spreading behavior of liquid Al on selected substrates. After high-temperature tests, the solidified Al/Cgr and Al/Ti couples were subjected to detailed structural observations by optical microscopy and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy.

References

[1] M.Y. Zhou, et al., Journal of Alloys and Compounds, 2020, 838, 155274.

[2] E. Fras, et al., COMPOSITES, 2003, 6, 120-124.

[3] K. Landry, et al., Materials Science and Engineering A, 1998, 254, 99-111.

[4] S. Terlicka, et al., Materials, 2022, 15(4), 9024.

[5] S. Terlicka, et al., Journal of Materials Engineering and Performance 2023, DOI: 10.1007/s11665-023-07950-1.

Acknowledgments

This research was supported by the National Science Centre of Poland within OPUS 22 project no. 2021/43/B/ST8/03271