Shraddha Sevlikar Materials Scientist

Metal–Metal Composites

Metal–Metal Composites & Hierarchical Materials

Building performance through engineered interfaces

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Layered metal–metal composite showing PVD layers, severe plastic deformation and interface evolution.
Layered metal–metal composite showing PVD layers, severe plastic deformation and interface evolution.

Scientific question

What happens at the interface when two dissimilar metals are bonded and then severely deformed together — and how does that interface control the composite?

Metallic systems where different metals, interfaces and microstructural levels are deliberately combined to create stronger and more reliable materials.

Research Scientist — University of Münster (September 2018 – January 2024)

My contribution

What I did

I built and studied model metal–metal composites in the Cu/Au, Cu/Ag, Ni/Cr and Ni/Cu systems, depositing the layers by physical vapour deposition and then processing them by severe plastic deformation.

My work covered the whole chain: deposition, ECAP and HPT processing, interface and microstructure characterisation, and mechanical testing. The aim was to establish what the interface does to bonding, phase evolution and mechanical response, rather than treating the composite as a simple sum of its two metals.

Methods

How it was measured

  • Systems: Cu/Au, Cu/Ag, Ni/Cr, Ni/Cu
  • Physical vapour deposition of the layers
  • Severe plastic deformation — ECAP and HPT
  • Interface bonding, reaction and evolution analysis
  • Compression and hardness testing
  • Microstructure and phase characterisation

See these methods in full on the Expertise page

Key findings

What the work showed

01

Interface reaction during deformation, not the bulk properties of either metal, sets the composite's response.

02

Severe plastic deformation both refines the microstructure and changes what the interface is made of.

03

Bonding quality and phase evolution at the interface track directly with the measured mechanical behaviour.

This work focuses on metallic systems where different metals, interfaces and microstructural levels are deliberately combined to create stronger and more reliable materials. By using severe deformation and hierarchical design, the research shows how interfaces can control mechanical response, stability and long-term performance.

The systems

Cu/Au, Cu/Ag, Ni/Cr and Ni/Cu, built from PVD-deposited layers and then driven through severe plastic deformation — high-pressure torsion (HPT) and 3D compression on specially designed shear-compression specimens.

The interface as a design variable

An interface is not simply where two metals meet. Under severe deformation it evolves: it reacts, it roughens, it stores defects, and it becomes the feature that decides whether the composite hardens gracefully or fails. Treating the interface as something to be designed — rather than something to be tolerated — is the core of this work.

Why it matters

Relevant wherever a joint or a coating has to carry load: lightweight strength, damage tolerance, thermal stability and reliable performance under complex loading depend on what the interface does, not on the two metals in isolation.

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