Seamless thermoplastic joining of ZrCu-based bulk metallic glasses via simple high-strain uniaxial compression

• A joining of Zr-based BMGs by a simple, scalable, thermoplastic method is demonstrated. • Exploits a unique amorphous structure for atomic-scale merging during superplastic flow. • Ensures local structural, chemical, and mechanical uniformity at the interface. • Only standard heating-compression equipment offers reliable control. • Method overcomes BMGs’ size limits, enabling the manufacturing of larger components. Bulk metallic glasses (BMGs) exhibit exceptional physicochemical properties, but their applications remain limited by casting size constraints. Existing joining methods for BMGs face challenges, including crystallization risk, difficulties in control, and complex equipment requirements. Here we show a simple, scalable thermoplastic joining method for Zr-based BMGs using high-strain uniaxial compression within the supercooled liquid region. Using a precursor of Zr 44 Cu 37 Ag 7 Al 7 Be 5 BMG with medium formability, we achieved successful macroscopic joining at 490 °C with strains of 30–70 %. We show that microscopic joining quality increases with applied strain, resulting in metallic bonding and microstructural integrity with local chemical and mechanical uniformity at 70 % strain. The proposed method exploits the unique homogeneous amorphous structure and viscous flow behavior of BMGs, enabling atomic-scale merging during deformation. This approach offers reliable control, reduced crystallization risks, and accommodation of complex geometries. The straightforward thermomechanical process requires standard heating-compression equipment, providing an effective solution to overcome BMG size restrictions and expand their practical applications in advanced systems requiring larger components.