Niobium C103 is a refractory alloy with niobium as the matrix and the addition of hafnium (approximately 10%) and titanium (approximately 1%). Due to its excellent high-temperature strength, good room-temperature plasticity, and weldability, it has become a key material for high-temperature components in aerospace. Traditionally, C103 components are mainly manufactured using subtractive methods such as forging and machining, but the material utilization rate is extremely low—traditional forging can result in material waste of up to 95%, and it is difficult to manufacture complex structures. The introduction of additive manufacturing technology has opened up a completely new path for the application of this material.
The core driving force behind additive manufacturing becoming a research hotspot for C103 alloys lies in its ability to overcome the limitations of traditional processing: firstly, it significantly improves material utilization and reduces manufacturing costs; secondly, it enables the integrated forming of complex geometries, shortening the manufacturing cycle. Especially in fields with urgent needs for complex heat-resistant structures, such as hypersonic vehicles and rocket engine thrust chambers, additive manufacturing is almost an irreplaceable solution.
Additive manufacturing first requires qualified raw materials. Currently, C103 additive manufacturing primarily utilizes two raw material forms: Powder raw materials: Spherical C103 powders are prepared through Electrode Induction Gas Atomization (EIGA) or Plasma Rotating Electrode Atomization (PREP) processes, with particle sizes typically ranging from 15-53 μm or 45-105 μm. High-quality spherical powders are the foundation for powder-based processes such as Laser Powder Bed Fusing (L-PBF). Wire raw materials: C103 welding wire is used directly for additive manufacturing, avoiding the complexity and cost of powder production, and is particularly suitable for manufacturing large-size components.
Currently, research on additive manufacturing of C103 alloys mainly focuses on the following two technical routes: Laser Powder Bed Fusing (L-PBF). L-PBF is currently the most extensively researched powder-based process. Institutions such as NASA's Glenn Research Center have systematically evaluated the mechanical properties of L-PBF-formed C103 from room temperature to 1400°C. Studies have shown that using spherical C103 powder with a particle size D50 of approximately 29 μm, dense parts with a relative density exceeding 99.8% can be fabricated in an inert atmosphere with an oxygen content below 200 ppm. However, the L-PBF process suffers from drawbacks such as a relatively low deposition rate and limited production scale.
Laser Directed Energy Deposition (DED) DED technology, due to its higher deposition efficiency and larger forming size, has become another important direction in C103 additive manufacturing. Based on the feed form, DED can be divided into powder-based DED and filament-based DED (LWDED):
Powder-based DED: Oak Ridge National Laboratory in the United States systematically optimized the process parameters of C103 powder-based DED through a combination of multiphysics melt pool simulation and experiments, finding that defect-free printed parts can be obtained when the power-velocity ratio (P/V) is close to 1.
Silk-based DED: A team from KAIST in South Korea reported for the first time a laser-fed DED process for C103, finding that a laser power of 2000-2600W is required to form a stable molten pool; excessive power can cause laser reflection and arcing, disrupting the deposition process. The yield strength of C103 formed by this process exceeds the ASTM B654 standard by more than 10%. Institutions such as Oregon State University in the United States are also developing C103 filament DED processes for the manufacture of thin-walled structures.
