With the rapid advancement of 3D printing (additive manufacturing) technology, demand for high-performance metal powders continues to grow, particularly in sectors such as aerospace, automotive, and medical applications. As a next-generation metal powder, titanium-based composite powders have become a research hotspot due to their exceptional properties, including light weight, high strength, and excellent corrosion resistance. However, conventional powder‑making methods suffer from issues such as uneven particle size, severe agglomeration, and compositional heterogeneity, which limit their practical applications. Recently, an innovative ultrasonic atomization technique has offered a promising new solution to these challenges.

This paper provides an in-depth exploration of the “Preparation and Performance Study of Multi-Scale Enhanced Titanium-Based Composite Powders via Ultrasonic Atomization,” proposed by Professor Dong Fuyu of Shenyang University of Technology and his colleagues, examining its processing route, microstructure, mechanical and functional properties, and potential future applications.

Limitations of Conventional Powder-Preparation Techniques

Traditional powder‑making methods primarily include mechanical grinding, atomization (such as flame atomization and gas atomization), and electrolysis. Although these techniques are widely employed in industrial production, they suffer from the following drawbacks:

• Irregular morphology: Powders prepared by mechanical grinding often exhibit irregular shapes and a porous structure, which can adversely affect the quality of subsequent sintering and forming processes.
• Unfavorable morphology: Although gas atomization can achieve a high degree of sphericity, it readily generates satellite particles, which degrade the powder’s flowability and spreading performance.
• Uneven particle size distribution: It is difficult to precisely control the particle sizes of various powders, which affects product consistency.
• Uncontrollable microstructure: It is prone to non-uniform elemental distribution, inclusions, and defects, which degrade material properties.

These issues are particularly pronounced in the fabrication of high-performance materials, especially metal matrix composites such as titanium-based composites.

The Emergence and Advantages of Ultrasonic Atomization Technology

Ultrasonic atomization technology uses high-frequency sound waves to atomize molten metal, producing fine, uniform, spherical powders. It offers significant advantages over conventional atomization methods:

1. High sphericity and purity

Ultrasonic vibration induces the formation of a stable liquid film on the melt surface, enabling gentle and uniform atomization that significantly enhances powder sphericity, reduces satellite particles, and improves flowability.

2. Particle size is highly controllable

By adjusting the ultrasonic frequency and amplitude, the powder particle size distribution can be precisely controlled, enabling efficient production of target particle sizes (e.g., 50–110 μm) and ensuring reliability for specialized applications.

3. Uniform microstructure

Ultrasonic vibration enhances the uniform stirring of the melt, promoting homogeneous elemental distribution, reducing inclusions and agglomeration, and improving the microstructural consistency of the powder.

4. Production of powders with special structures

As demonstrated in the paper, ultrasonic atomization can fabricate complex multi-scale composite structures—such as the incorporation of nanoscale TiB steel fibers and Ti5Si3 particles—thereby significantly enhancing the mechanical properties and microstructure of the powder.

5. Compatible with multiple metals

In addition to low-melting-point metals such as steel and aluminum alloys, ultrasonic atomization is also suitable for high-melting-point alloys—including titanium alloys and powder‑metal ceramic composites—thereby broadening its range of applications.

Research Methodology

This study employed ultrasonic atomization (UA) technology to prepare a titanium-based composite powder featuring a dual‑structured reinforcement phase. Using Ti6Al4V alloy as the matrix, two reinforcing phases—TiB and TiC—were introduced via an in situ reaction, resulting in a composite microstructure in which both nanoscale particles and rod‑like features are uniformly embedded. The effects of ultrasonic atomization process parameters on powder morphology, particle size distribution, microstructure, and mechanical properties were systematically investigated.

Experimental results

01 Powder Morphology and Particle Size:

• The powder particles are highly spherical, with no obvious satellite particles or agglomeration.
• The particle size distribution is concentrated between 35 and 150 μm, making it suitable for additive manufacturing.

02 Microstructure:

• The reinforcing phase is uniformly distributed within the Ti6Al4V matrix in two morphologies: nanoparticles and elongated rod-like particles.
• The interface between the reinforcement phase and the matrix exhibits good bonding, with no obvious cracks or porosity.
• A typical “dual-structure” reinforcement system has been established, balancing strength and toughness.

03 Mechanical Properties:

• Nanoindentation tests reveal that the nanoparticle hardness reaches as high as 7.564 GPa.
• Compared with the unenhanced Ti6Al4V powder, the hardness and strength are significantly improved.

Image and Text Guide

Figure 1. Flowchart of the experimental procedure

Figure 2. Schematic diagram of the ultrasonic atomization device.

Figure 3. Particle size distribution and mass ratio of TMCs powders prepared by ultrasonic atomization.

Figure 4. Scanning electron microscope images of TMC powder particles: (A) 35–60 μm powder; (B) High-magnification image of the red‑boxed particles in (A); (C) Particle size distribution of the 60–110 μm powder; (D) High-magnification image of the red‑boxed particles in (C); (E) Particle size distribution of the 110–150 μm powder; (F) High-magnification image of the red‑boxed particles in (D); (G) Particle size distribution of the 110–150 μm powder; (H) High-magnification image of the red‑boxed particles in (G); (I) Particle size distribution corresponding to the image in (G).

Figure 5. a) Micro-CT images of TMC powder particles: (A) Three-dimensional reconstruction; (B) Reconstruction obtained by extracting a 1-mm‑edge cube from (A) and removing boundary particles; (C) (B); (D)–(F) Powder porosity in different orientations; (G)–(I) Analysis results for the powder and its porosity.

Figure 6. Schematic diagram of the ultrasonic atomization mechanism.

Figure 7. XRD pattern of TMC powder particles.

Figure 8. Cross-sectional microstructure and line-scan EDS results of TMC powder particles: (a) cross-sectional microstructure of the powder, (b) high-magnification image of the red box in (a), (c) the yellow‑line region in (b), and (d) the EDS spectrum obtained along the yellow line in (c).

Figure 9. EBSD maps of TMC powder cross-sections: (a) inverse pole figure of the powder cross-section, (b) phase distribution map of the powder cross-section, (c) particle size distribution plot.

Figure 10. Schematic illustration of the microstructure of powder formed by ultrasonic atomization of droplets.

Figure 11. TEM characterization of the TiB phase in the cross-section of TMC powder particles: (a) TEM image of the powder cross-section; (b)–(f) SAED patterns and EDS spectra of the TiB phase within the red‑boxed region in (a); (g) HRTEM image of the red‑boxed region in (a); (h) high‑magnification image of the red‑boxed region.

(g), (I)–(j) FFT images of the red‑dot and yellow‑line regions in (h); (k)–(l) IFFT images of the same regions; (k1)–(l1) measurements of the lattice spacing in the marked areas of (k) and (l).

Figure 12. TEM characterization of the Ti5Si3 phase in the cross-section of TMC powder particles: (a) TEM image of the powder cross-section; (b)–(f) SAED patterns and EDS spectra for the region enclosed by the red box in (a); (g) HRTEM image of the region enclosed by the red box in (a); (h) high-magnification image of the region enclosed by the red box in (g).

(I)–(j) FFT images of the red‑dot and yellow‑line regions in (h); (k)–(l) IFFT images of the same regions; (k1)–(l1) measurements of the lattice spacing in the marked areas of (k) and (l).

Figure 13.2 Nanoscale indentation tests on TMC powder cross-sections at an loading rate of 2 mN/s and a load of 15 mN: (a)–(b) Load–displacement curves and surface topography of the nanoindents; (c) Hardness and elastic modulus of the nanoindents.

This study is the first to successfully prepare titanium-based composite powders with a dual‑structured reinforcement phase using ultrasonic atomization. This approach effectively addresses the issues of non‑uniform reinforcement distribution and poor sphericity inherent in conventional fabrication methods, yielding powders with excellent sphericity, density, and mechanical properties, making them well suited for high‑performance additive manufacturing applications.

This achievement offers a new approach to the preparation of titanium-based composite powders, expands the application scope of ultrasonic atomization technology in the field of metal matrix composites, and holds significant implications for advancing additive manufacturing of high-performance components in aerospace and other sectors.