I. Bottlenecks in the Development of Traditional Flour-Milling Technology

Mainstream additive manufacturing processes such as laser powder bed fusion, electron beam melting, and direct energy deposition impose stringent requirements on powder morphology; powders with high sphericity and a narrow particle-size distribution are essential for ensuring process stability.

Currently, the industry’s mainstream processes—gas atomization, water atomization, and plasma/induction spheroidization—are well suited for large‑scale industrial powder production, yet they suffer from significant drawbacks: the equipment is bulky, production changeovers are costly, and these systems cannot be flexibly deployed in universities or research institutions. Moreover, they impose substantial restrictions on the types of feedstock materials, forcing researchers to rely on mixed powders or non‑spherical powders for experiments. This often leads to uneven alloy compositions and reduced powder flowability, severely hindering the exploration of novel alloy systems.

II. Ultrasonic Atomization Powdering Technology: Core Principles and Technical Advantages

(1) Technical Principle

Ultrasonic atomization is the core technology investigated in this paper. Its principle differs from conventional high‑velocity fluid‑impact powder production: it relies on high‑frequency vibrations to overcome the surface tension of liquid metal, causing the molten metal to detach from the bulk and form tiny droplets. These droplets then cool and solidify naturally in the surrounding atmosphere, ultimately yielding spherical metal powders.

This process can be paired with two mainstream melting methods: plasma heating is suitable for producing high‑temperature alloys, while induction heating is ideal for low‑melting-point alloys. It can also be integrated with an arc‑melting module, expanding its applicability to scrap metal recycling. The equipment supports small‑batch pilot production, with powder‑production capacities flexibly adjustable from 1 gram to several kilograms, perfectly meeting the research needs of rapid validation for novel alloy formulations.

(II) Core Advantages

• Device miniaturization: No high‑speed fluidic system is required, and the atomization chamber volume has been significantly reduced, enabling deployment in laboratories and research institutions.
• Wide raw material compatibility: The melting unit can directly accommodate various feedstocks, including metal strips, machining chips, and ingots, thereby streamlining the pre‑powdering process.
• The powder exhibits excellent quality: it features high sphericity, a narrow particle-size distribution, and minimal compositional segregation, with outstanding bulk density and flowability.
• Flexible process integration: It can be combined with arc melting to produce powdered recycled metals, thereby promoting closed-loop material utilization.

Leveraging this technology, the research team has successfully synthesized a variety of tailored powders, including zirconium-based metallic glass powders, platinum‑based high‑temperature alloys, modified magnesium alloys, aluminum alloys, and magnetocaloric functional alloys, spanning both structural and functional materials.

III. Experimental Study on Typical Material Applications and Analysis of Results

This study selected C103 High-Temperature Alloy, Silver-Modified Magnesium Alloy, Recycled Titanium Alloy Three representative materials were selected, and ultrasonic atomization-based powder‑making experiments were conducted. Their properties were characterized using scanning electron microscopy, energy-dispersive spectroscopy, particle size analysis, and other techniques.

(1) C103 Niobium-Based High-Temperature Alloy

C103 alloy is a refractory high‑temperature alloy used in aerospace, rocket propulsion systems, and hypersonic vehicles. It was employed in the Apollo lunar module’s rocket nozzles and is predominantly utilized for thin‑walled precision components, demanding exceptionally high powder purity and microstructural homogeneity.

The experiment employed a TZM alloy horn operating at a vibration frequency of 40 kHz to perform ultrasonic atomization on narrow strips of C103 alloy. The test results indicate:

• The powder exhibits a nearly spherical morphology, with a uniform dendritic microstructure internally, a narrow particle size distribution, and high bulk density and flowability—properties essential for additive manufacturing.
• Energy-dispersive X-ray spectroscopy (EDS) analysis revealed no oxide inclusions or elemental segregation, indicating excellent powder purity that meets the performance requirements for high-end high-temperature components.

(II) Silver-Modified Magnesium Alloy

Magnesium alloys exhibit excellent biodegradability and, once implanted in the human body, do not release toxic ions, making them an ideal material for orthopedic implants. When doped with silver, they can both match the rate of bone healing to regulate corrosion and impart antibacterial properties to the alloy.

This material employs Induction melting + ultrasonic atomization The process operates at a working frequency of 60 kHz. Given the low boiling point of zinc in the alloy, which leads to easy evaporation at elevated temperatures, the research team employed an arc-melting module to prepare a silver–magnesium master alloy, effectively mitigating the loss of volatile elements. The compositional deviations of the self‑made master alloy are significantly lower than those of commercially available products.

Experimental observations and conclusions: After atomization, sub-micron particles are present on the powder surface, formed by the condensation and deposition of evaporated zinc. Moreover, high temperatures can readily lead to particle agglomeration. This issue can be mitigated by increasing the nozzle diameter and optimizing the pouring temperature, among other measures. The resulting powder exhibits a particle size suitable for laser powder bed fusion, demonstrating significant application potential.

(3) Recycling of titanium alloys (reutilization of titanium machining chips)

Titanium alloys are critical strategic materials in the aerospace industry, and the recovery and recycling of titanium machining chips are essential for advancing material sustainability and establishing a closed-loop industrial chain.

Experimental procedure: Titanium alloy chips generated by a CNC machine tool are placed in a copper cooling crucible and melted into ingots via plasma arc melting. The resulting ingots are then atomized into powders using the same ultrasonic atomization equipment employed for the C103 alloy, with plasma process parameters adjusted to minimize aluminum evaporation.

1. Powder Morphology and Particle Size

The finished powder exhibits exceptionally high sphericity and a narrow particle-size distribution, with over 85% of the particles smaller than 100 μm. It is compatible with a variety of powder metallurgy processes, including laser powder bed fusion, electron beam melting, and hot isostatic pressing. Particle-size parameters are provided in the table below:

2. Purity Index

After milling, the total oxygen content of the material increased by only 220 ppm, with the overall oxygen level remaining below 600 ppm—fully compliant with the ASTM F2924 industry standard. The recycled powder is ready for direct use in industrial applications.

IV. Research Summary and Industry Value

• Ultrasonic atomization technology is well-suited for the development of multi-component alloys: it enables the stable production of C103 high-temperature alloy powders with uniform microstructures and excellent morphologies, making it an ideal powder‑making approach for advanced refractory alloys. For low-melting-point materials containing highly volatile elements, such as silver‑modified magnesium alloys, precise control of pouring temperature and melting parameters is essential to prevent elemental evaporation and particle agglomeration.
• Enabling Closed-Loop Recycling of Strategic Metals: By integrating arc melting with ultrasonic atomization, titanium alloy machining chips can be efficiently converted into high‑quality spherical powders, with recycled powder properties meeting stringent specifications, thereby providing a mature technological solution for the circular utilization of metals such as titanium and magnesium.
• Driving innovation in the additive manufacturing industry: Compared with conventional powder‑making processes, ultrasonic atomization offers miniaturization, lower costs, and greater customization, thereby lowering the barriers to developing new alloys. This not only accelerates the iteration of novel material formulations but also provides a groundbreaking technological pathway for the green and sustainable development of the powder metallurgy sector.

In the future, as process optimization continues, ultrasonic atomization powder‑making technology will play an increasingly significant role in the research and development—and recycling—of advanced functional alloys, biomedical materials, and high‑end structural materials for aerospace applications.

Image and Text Guide

Figure 1: Repulverization chamber for atomizing C103 alloy

Figure 2 Ultrasonic atomization of the molten alloy flow in the crucible using induction heating: (A) A novel magnesium alloy modified by silver forms an atomized spray. (B) Copper alloys, on the other hand, generate a focused stream of atomized particles.

Figure 3. Arc melting process of silver–magnesium alloy: (A) Magnesium alloy combined with visible silver particles when processed under reduced current settings; (B) Homogenized master alloy (approximately 120 mm in length).

Figure 4 SEM images of niobium C103 alloy powder: (A) Macrostructure view; (B) Its microstructure

Figure 5 Energy-dispersive X-ray spectrum: (A) Composite element, (B) Niobium detection, (C) Nickel testing, and (D)

Figure 6. Morphology of silver-modified magnesium alloy powder

Figure 7 Titanium-based powder prepared from recycled machining chips using ultrasonic atomization technology.

Figure 8 Particle Size Distribution — (A) Based on volumetric analysis, (B) Quantity-based analysis