Research Profile - Department of Materials Science and Metallurgy ...

Rob Wallach
Senior Lecturer
MA University of Cambridge
MSc Queen’s University, Canada
PhD University of Cambridge
+44 (0) 1223 334330
erw1@cam.ac.uk
www.msm.cam.ac.uk/joining
Joining of Materials
Individual materials are becoming more specialized and are
designed to optimize their performance for specific applications.
However for most applications, these highly developed materials
have to be joined to others in a manner that ensures a minimal
loss in properties or performance. This requires developing
new processes and/or the refinement of existing approaches.
This forms the basis of my research which is focused on joining
materials, generally advanced but not exclusively so, with the
emphasis on modelling processes, joint formation and predicting
the properties of materials after they are joined.
Diffusion bonding
Our work has focused on fundamental modelling of various
processes and on devising a flux-free diffusion-based approach
using gallium to join alloys with oxide films. This patent-protected
approach has been proven for aluminium, stainless steel and
nickel-base superalloys, and has been extended to joining
metallic foams to solid metal components. Strengths matching
the parent materials are attainable and as well as the fabrication
of dissimilar metal joints.
Predicting the performance and modelling the
reliability of lead-free soldered joints
Lead-free solders are replacing conventional tin-lead eutectic
solder on environmental grounds. These new alloys are being
evaluated (e.g. data on creep and fatigue properties) and likely
failure mechanisms identified.
High-energy welding processes (electron-beam and
laser welding)
We have modelled the microstructures and properties of laser and
hybrid welds in structural and pipe-line steels. Existing models
for predicting weld metal and heat affected zone microstructures,
and the mechanical properties of laser welds in structural steels
are being evaluated. This follows previous research on predicting
the formability after laser welding automobile steels to aid
lightweight car production.
H Assadi, AA Shirzadi & ER Wallach, “Transient liquid phase diffusion
bonding under a temperature gradient: Modelling of the interface
morphology” Acta Mater. 49, 31–39 (2001).
AA Shirzadi & ER Wallach, “To provide a non-chemical method to remove
the surface oxide from various alloys to improve bonding, and coating
processes.” British Patent Application 2005, GB2380491; USA Patent
Application 2003, 6,669,534 B2, 30.
S Turan, D Turan, IA Bucklow & ER Wallach, “The effect of metal coating
on the strength of capacitor-discharge joining of oxide ceramics” Key Eng.
Mater. 264–268, 687–690 (2004).
P Moore, D Howse & ER Wallach, “Microstructure and properties of laser/
arc hybrid welds and autogenous laser welds in pipeline steels” Sci.
Technol. Welding Joining 9, 314–322 (2004).
Diffusion bonds between dissimilar metals (aluminium and
titanium) showing excellent mechanical strength
Research Profile 37