Lanthanum Refines Grain Structure in Copper Alloy

A study published in the Journal of Materials Science reported that the addition of 0.058 wt.% lanthanum to a copper-nickel-silicon alloy significantly refines the grain structure and improves strength. The study, published on November 1, 2026, focused on a specific alloy composition designated as Cu-2.54Ni-0.54Si-0.058La, which was fabricated using an upward continuous casting process. The primary objective was to investigate both the as-cast microstructure and the hot deformation behavior of this material. By introducing 0.058 wt.% lanthanum, the team observed the formation of La-containing primary phases that played a critical role in the material’s final properties.

The experimental design involved conducting hot compression tests on a Gleeble-3800D thermo-mechanical simulator. The tests were carried out over a temperature range of 550 to 850 degrees Celsius and at strain rates varying from 0.01 to 10 per second. This wide range of conditions allowed the researchers to obtain compressed specimens and corresponding true stress-strain curves under all tested scenarios. The combination of microstructural characterization of both as-cast and deformed specimens, along with the analysis of these stress-strain curves, provided a comprehensive view of the alloy’s behavior. The results revealed that the La-containing primary phases effectively pinned grain boundaries, which inhibited grain growth and led to significant grain refinement.

A key quantitative finding from the study was the calculation of the hot deformation activation energy using the Arrhenius constitutive model. The calculated value for the Cu-Ni-Si-La alloy was 639.782 kJ/mol. This figure is approximately 7.59% higher than that of the La-free Cu-Ni-Si alloy, indicating that the presence of lanthanum increases the energy required for deformation.

The study also examined the mechanisms of dynamic recrystallization (DRX) in the alloy. DRX was found to occur not only under high-temperature and low-strain-rate deformation conditions but also under low-temperature and high-strain-rate conditions. The mechanism involves local stress concentration caused by dislocation pile-ups, which induces the formation of shear deformation bands.

Furthermore, the research highlighted the role of adiabatic temperature rise in triggering dynamic recrystallization. The resulting fine DRX grains were predominantly distributed around the shear deformation bands.

While the study provides valuable insights into the role of lanthanum in this specific alloy system, it is limited to the particular composition and processing conditions tested. The findings are specific to the Cu-2.54Ni-0.54Si-0.058La alloy prepared by upward continuous casting and subjected to hot compression within the specified temperature and strain rate ranges. However, the current results demonstrate that even a small addition of lanthanum can have a significant impact on the grain structure and strength of copper-nickel-silicon alloys.

Subject of Research: Microstructure and hot deformation of Cu-Ni-Si-La alloy

Article Title: Study on as-cast microstructure and hot deformation behavior of Cu-2.54Ni-0.54Si-0.058La alloy prepared by upward continuous casting

Article References: Yan, L., Gao, Z., Chen, S., Wang, S., Song, H., & Zhang, S. (2026). Study on as-cast microstructure and hot deformation behavior of Cu-2.54Ni-0.54Si-0.058La alloy prepared by upward continuous casting. Journal of Materials Science. https://doi.org/10.1007/s10853-026-13875-6

Image Credits: AI Generated

DOI: 10.1007/s10853-026-13875-6

Keywords: copper alloy, lanthanum, hot deformation, microstructure, grain refinement, dynamic recrystallization, continuous casting, materials science, activation energy, stress-strain, as-cast, deformation