Micro-honeycomb structures with various pitches between adjacent cells were hot-embossed on Zr₃₅Ti₃₀Cu_8.25Be_26.75 bulk metallic glass surface. The effect of pitch geometry on the frictional behavior of metallic glass surface was systematically investigated. The results revealed that all textured metallic glass surfaces show a reduction in friction coefficient compared to smooth surface. More intriguingly, the friction coefficient first decreased and then increased gradually with increasing pitches. Such unique behavior can be understood fundamentally from the perspective of competing effects between contact area and local stress level with increasing pitches. This finding not only enhance the in-depth understanding of the mechanism of the significant role of surface topography on the frictional behavior of metallic glass surface, but also opens a new route towards other functional applications for bulk metallic glasses.

Inspired by the aseismic structure of skyscrapers, Ti6Al4V frames with tubular structure were designed, 3D printed and thermoplastic formed with Zr₃₅Ti₃₀Be_26.75Cu_8.25 bulk metallic glass matrix under ultrasonic vibration, forming sandwich-structured bulk metallic glass composites. The interface characterization between matrix and frame reveals a typical metallurgical bonding. By tuning the geometry of Ti6Al4V frame, the composites manifest an enhanced fracture toughness of 213 MPa m^1/2, 2.3 times higher than that of the monolithic bulk metallic glass. Our findings provide a promising route for the development of metallic composites. Highlights GRAPHICAL ABSTRACT IMPACT STATEMENT A promising route for the design and fabrication of bulk metallic glass composites with tailored mechanical properties was developed by combing ultrasonic vibration-assisted thermoplastic forming and 3D printing.

The interfacial friction behaviour of Zr₃₅Ti₃₀Be_26.75Cu_8.25 metallic glass during micro-extrusion was investigated at various strain rates and temperatures in the supercooled liquid region. A friction mechanism map that distributes adhesion regime, furrow regime and mechanical engagement regime was constructed. These regimes respectively correspond to Newtonian flow, non-Newtonian flow and inhomogeneous flow by comparing with the typical deformation map. The correlation between flow characteristics and interfacial friction behaviour is well analysed by combining the viscosity theory with the finite-element simulations.