I. Pain Points of Conventional Medical Titanium Alloys and Approaches to Developing New Alloys

Titanium alloys, owing to their high strength, excellent biocompatibility, and superior corrosion resistance, have long been employed in biomedical implant applications. Currently, the materials commonly used in clinical practice are… Ti-6Al-4V Alloys have significant drawbacks: the aluminum and vanadium elements they contain exhibit biological toxicity, posing safety risks with long-term implantation; meanwhile, commercially pure titanium lacks sufficient strength to meet the performance requirements of load-bearing implants.

To this end, the research team selected Tantalum, zirconium, ruthenium, copper Developing a novel titanium-based alloy using non-toxic elements:

• Tantalum, as a β‑stabilizing element, and zirconium, as a solid‑solution strengthening element, synergistically enhance the alloy’s strength and corrosion resistance; moreover, zirconium can form a protective passive film on the alloy surface.
• Trace amounts of ruthenium do not alter the alloy’s microstructure, further enhance its corrosion resistance, and are non‑toxic to humans.
• Copper is a core functional element, Add 5% by mass of copper. It enables the alloy to exhibit stable antibacterial properties, meeting the antibacterial requirements of dental implants.

Finalize Ti-6Ta-1.5Zr-0.2Ru-5Cu (mass percent) Alloy formulation aimed at developing a next-generation medical-grade titanium alloy that balances mechanical properties, biocompatibility, and antibacterial performance.

II. Process Selection for Additive Manufacturing: The Stringent Requirements of L-PBF for Powder Materials

Compared with casting and conventional powder metallurgy, additive manufacturing enables the one‑step fabrication of customized implants with complex geometries, resulting in a more streamlined process. In this study, we selected… Laser Powder Bed Fusion (L-PBF) A forming trial was conducted using this process, which imposes stringent specifications on the raw powder:

• Appearance: The powder shall be Spherical , ensuring liquidity and spreadability;
• Particle size: Applicable range 10–100 μm; the industry‑standard optimal range is 15–45 μm.

Conventional milling methods struggle to simultaneously optimize sphericity and particle size distribution; in this study, we employed… Ultrasonic atomization technology The preparation of alloy powders has been completed, which also represents the core technical highlight of this study.

III. Detailed Explanation of Ultrasonic Atomization Powder-Production Technology

In this study, the rePowder ultrasonic atomization system from AMAZEMET was employed to produce small‑batch powders under standard laboratory conditions, with the entire process conducted in an inert argon atmosphere to prevent alloy oxidation.

1. Technical Principle

Ultrasonic atomization belongs to Liquid–Solid Conversion Milling Process , suitable for high‑melting‑point, highly reactive alloys such as titanium: the mixed feedstock is directly melted at elevated temperatures within an ultrasonic horn, with ultrasonic vibrations inducing the formation of uniform droplets; once detached from the liquid film, the droplets undergo rapid cooling and solidify into a solid powder.

• Key influencing factor: Ultrasonic frequency determines the final particle size distribution; a frequency of 40 kHz enables the production of powders with a median particle size (D50) of 45–60 μm, which is ideally suited to the L-PBF process.
• Technical advantages: narrow powder particle size distribution, raw material utilization rate exceeding 80%, and high product purity.

2. Specific experimental parameters

• Raw material ratio: A total of 100 g of pure elemental powders, blended in the Ti–6Ta–1.5Zr–0.2Ru–5Cu composition, are thoroughly mixed using a dedicated powder mixer and subjected to pressure compaction as a pre‑treatment.
• Equipment parameters: molybdenum alloy horn, ultrasonic frequency 40 kHz, current 155 A, horn amplitude 180–280 W (rated at 100%–130%).
• Environmental parameters: argon flow rate of 7 L/min, continuous argon‑atmosphere shielding, and sealed storage of the collected powder.

3. Detection Methods

Used before and after the experiment Malvern laser particle size analyzer, scanning electron microscope–energy-dispersive X-ray spectrometer (SEM-EDX), X-ray diffractometer (XRD) The three major instruments sequentially characterize the powder morphology, elemental distribution, phase composition, and particle size distribution, and perform microstructural analysis on powder cross-sections.

IV. Experimental Results and Performance Analysis

1. Powder Morphology and Elemental Distribution

Before atomization, the elemental mixed powder particles exhibit an irregular morphology, with significant variations in particle size among different elements; ruthenium and zirconium, due to their low mass fractions, are difficult to distinguish. After ultrasonic atomization, The vast majority of the powders exhibit a standard spherical shape. , meeting the L-PBF morphological requirements. The atomization process enables in-situ alloying, resulting in a uniform distribution of all elements within the spherical powder; only a small number of irregular, large particles are present, originating from fragmentation prior to melting and particle agglomeration—defects that are secondary to the process.

Microscopic examination of powder cross-sections revealed trace porosity within the particles, with compositional segregation observed in some agglomerates: small, irregular particles contain virtually no tantalum or ruthenium, while ruthenium exhibits slight depletion due to its high density and low concentration. The measured zirconium content is lower than the theoretical value, suggesting that errors were introduced during the raw-material weighing process.

2. Ingredient Comparison (Mass Percentage)

Table

Overall, The composition of the large-sized spherical powder is highly consistent with the design values. , is a high-quality powder that is readily available; irregularly shaped particles exhibit significant compositional deviations and can be removed by sieving.

3. Particle Size Distribution

Table

After atomization, the powder’s D50 is 58.3 μm, falling within the optimal particle-size range for L-PBF; no particles smaller than 10 μm are present, and the overall particle-size distribution is narrow. Only a small number of agglomerated large particles around 800 μm are observed; further optimization of the particle-size distribution can be achieved by sieving with a 200-μm mesh.

4. Phase Analysis (XRD)

Before atomization, the powder exhibited only the characteristic peaks of the individual elemental components; after ultrasonic atomization alloying, the spectrum showed… α-Ti, β-Ti Titanium alloy characteristic phase, simultaneously detected Ti₂Cu Phase. This phase is key to the alloy’s antibacterial properties, fully meeting the design requirements for biomedical applications. Due to the detection limit, low concentrations of zirconium and ruthenium were not detected, while the characteristic peak of copper was obscured by the background signal from fine particles.

V. Research Conclusions

• Ultrasonic atomization technology enables the stable production of Ti-6Ta-1.5Zr-0.2Ru-5Cu alloy powders suitable for the L-PBF process. The final product consists predominantly of spherical particles with an average particle size of 58.3 μm and a narrow particle-size distribution; the predominant particle composition and phase structure both meet the standards for biomedical additive manufacturing.
• The process exhibits minor defects: localized particle agglomeration, compositional segregation, and the loss of trace elements. Large-sized irregular particles are removed using a screening mesh. , which can significantly enhance powder quality;
• This alloy powder combines mechanical performance with antibacterial and biocompatible properties, offering strong industrialization potential in fields such as dental and other customized medical implants; it also demonstrates the practicality of ultrasonic atomization technology for producing highly reactive, multi-component medical titanium alloys.

This study provides empirical data supporting the additive manufacturing of a novel nontoxic antibacterial titanium alloy and identifies avenues for optimizing the ultrasonic atomization process used to produce medical-grade metal powders.

Image and Text Guide

Figure 1. Fully equipped rePower system

Figure 2. SEM–BSE images of a powder mixture of titanium (Ti), tantalum (Ta), zirconium (Zr), ruthenium (Ru), and copper (Cu) prior to atomization: (a) low-magnification image; (b) high-magnification image.

Figure 3. EDX elemental distribution maps of the mixed powder containing titanium (Ti), tantalum (Ta), zirconium (Zr), ruthenium (Ru), and copper (Cu) prior to atomization.

Figure 4. SEM-SE images of Ti‑6Ta‑1.5Zr‑0.2Ru‑5Cu (in weight percent) powder after atomization: (a) low-magnification image; (b) high-magnification image, showing numerous spherical particles and one irregular particle.

Figure 5. EDX spectrum of the dispersed Ti-6Ta-1.5Zr-0.2Ru-5Cu (in weight percent) powder.

Figure 6. SEM-BSE image of the cross-section of Ti-6Ta-1.5Zr-0.2Ru-5Cu (in weight percent) powder, with arrows indicating the internal pore structure.

Figure 7. EDX elemental distribution maps of the cross sections of several atomized powder particles of Ti-6Ta-1.5Zr-0.2Ru-5Cu (in weight percent).

Figure 8. SEM-BSE image showing the location of the EDX analysis region within a cross-section of an atomized powder particle.

Figure 9. Particle size distribution of a powder mixture containing titanium (Ti), tantalum (Ta), zirconium (Zr), ruthenium (Ru), and copper (Cu) prior to atomization.

Figure 10. Particle size distribution of Ti-6Ta-1.5Zr-0.2Ru-5Cu (in weight percent) powder after atomization.

Figure 11. SEM-SE image showing the aggregation of fragmented particles.

Figure 12. XRD pattern of the mixed-element powder prior to atomization.

Figure 13. XRD patterns of Ti-6Ta-1.5Zr-0.2Ru-5Cu (in weight percent) powder after atomization.