The addition of 1000 ppm solute titanium substantially enhances the grain-refining performance of aluminum–vanadium–boron (Al–V–B) master alloys when inoculated into cast aluminum–7 weight percent silicon (Al-7 wt.% Si) alloys. In a laboratory investigation, introducing solute titanium markedly reduced grain dimensions across different master alloy formulations, achieving average grain sizes between 287.77 ± 33.75 micrometers and 356.52 ± 35.01 micrometers depending on the specific vanadium-to-boron atomic ratio.

Al–V–B master alloys represent promising grain refiners for cast aluminum–silicon alloys primarily due to their resistance to silicon poisoning and refinement fading. Despite these advantageous properties, the precise influence of added solute elements on the grain-refining efficiency of Al–V–B master alloys containing distinct particle compositions had previously remained unclear.

To investigate this relationship, researchers prepared three distinct Al–V–B master alloys possessing vanadium-to-boron atomic ratios of 1:1, 1:2, and 1:4 using an industrially relevant fluoride-salt synthesis method. The resulting alloys were designated based on their compositions as Al-1V-0.212B for the 1:1 ratio, Al-1V-0.424B for the 1:2 ratio, and Al-1V-0.848B for the 1:4 ratio.

Microstructural and phase analyses revealed that the phase constituents within the master alloys varied markedly according to the vanadium-to-boron atomic ratio. When the atomic ratio was higher than 1:2, as in the Al-1V-0.212B formulation, the alloy consisted predominantly of alpha-aluminum, Al3V, and VB2 phases. At the 1:2 ratio in Al-1V-0.424B, the microstructure comprised mainly alpha-aluminum and VB2. When the atomic ratio fell below 1:2, the Al-1V-0.848B alloy consisted mainly of alpha-aluminum, VB2, and AlB2 phases.

The grain-refining performance of all three master alloys was systematically evaluated in Al-7 wt.% Si alloys under several solute conditions. When inoculated into the base Al-7 wt.% Si alloy without additional solute elements, each of the three master alloys demonstrated only limited grain refinement. Furthermore, experimental additions of 4000 ppm magnesium or 1000 ppm iron failed to appreciably improve the refining performance of any of the master alloys under the tested experimental conditions.

In contrast to magnesium and iron, the incorporation of 1000 ppm titanium produced a substantial enhancement in grain refinement across all three master alloy variants. Specifically, inoculation with Al-1V-0.212B in the presence of 1000 ppm titanium yielded an average grain size of 356.52 ± 35.01 micrometers in the Al-7 wt.% Si cast alloy. Applying Al-1V-0.424B achieved a further reduced average grain size of 290.38 ± 25.50 micrometers, while the Al-1V-0.848B master alloy yielded an average grain size of 287.77 ± 33.75 micrometers.

These experimental results demonstrate that solute titanium plays an essential role in facilitating effective grain refinement in Al-7 wt.% Si alloys treated with Al–V–B master alloys. Furthermore, the magnitude of the refining enhancement depends directly on the vanadium-to-boron atomic ratio and the corresponding phase constituents present within the master alloy structure.

Subject of Research: Grain refinement of Al-7 wt.% Si alloys using Al-V-B master alloys and solute titanium

Article Title: Effect of solute Ti on the grain-refining performance of Al–V–B master alloys in Al‑7wt.%Si alloys

Article References: Zhou, Y., Wang, J., Chen, Z., Qian, J., Ding, M., Song, Y., Song, C., Liu, L., & Zhang, Y. (2026). Effect of solute Ti on the grain-refining performance of Al–V–B master alloys in Al‑7wt.%Si alloys. Journal of Materials Science. https://doi.org/10.1007/s10853-026-14117-5

Image Credits: AI Generated

DOI: 10.1007/s10853-026-14117-5

Keywords: Al-V-B master alloys, solute titanium, grain refinement, Al-7 wt.% Si, cast aluminum alloys, fluoride-salt method, vanadium-boron atomic ratio, Al-1V-0.212B, Al-1V-0.424B, Al-1V-0.848B, alpha-Al, Al3V phase, VB2 phase, AlB2 phase, silicon poisoning, refinement fading, solute magnesium, solute iron