Development of low-energy mechanical alloying technology to enable mass production of ODS-Cu alloys for fusion divertors

• A scalable mechanical alloying route for ODS-Cu alloys was explored by comparing high-energy attritor milling and low-energy Emax milling. • A PCA-free low-energy mechanical alloying strategy was proposed, leveraging the high ductility and low hardness of Cu. • The low-energy MA Cu–Hf alloy exhibited an excellent strength–ductility balance (UTS 347 MPa, elongation 36.4%). • This processing strategy shows strong potential for large-scale fabrication of high-performance ODS-Cu alloys for fusion applications. Oxide dispersion-strengthened Cu (ODS-Cu) alloys fabricated by mechanical alloying (MA) exhibit high thermal conductivity, excellent strength, and good resistance to neutron irradiation, making them promising heat-sink materials for divertors in DEMO (demonstration fusion power plant) reactors. However, the high ductility of Cu powders renders them prone to cold welding and agglomeration during MA, which significantly limits the mass production of ODS-Cu alloy powders. To identify a scalable ball-milling route for the large-scale production of ODS-Cu alloys, Cu–1.0Y 2 O 3 –1.5Hf (wt.%) and Cu–0.85Hf (wt.%) alloys were comparatively fabricated by high-energy and low-energy MA using an industrial attritor mill and a laboratory-scale Emax mill, respectively. Comprehensive characterization of the microstructure, mechanical properties, and thermal diffusivity was conducted. The results show that high-energy MA requires stearic acid as a process control agent (PCA) to improve powder recovery but induces pronounced pore formation and carbon contamination. To demonstrate a PCA-free dispersion-strengthening approach, a low-energy MA strategy was adopted. Under low-energy milling conditions of 300 rpm and a short milling duration of 12 h using the laboratory-scale Emax mill, the Cu–Hf alloy without PCA addition achieved a uniform dispersion of Hf core–HfO 2 shell nanoparticles with an average diameter of 4.90 nm and refined grains of 2.73 μm, yielding a favorable ultimate tensile strength of 347.42 MPa and an outstanding elongation of 36.4%. These findings demonstrate that PCA-free low-energy MA enables high powder recovery and produces bulk ODS-Cu alloys with an excellent balance of mechanical strength and thermal conductivity, offering strong potential for the large-scale fabrication of fusion divertors.