David J. Browne
Professor David J. Browne is a metallurgist with a particular interest in phase transformations during metals processing. His Ph.D. is from Oxford University (where the degree is known as D.Phil.), Department of Materials, on computational modelling of microstructural evolution during alloy solidification. David leads the Phase Transformation Research Group at UCD, which concentrates on both experimental and theoretical/modelling investigations into processes such as casting, welding and additive manufacture. David has invented and patented novel metal casting processes, has developed computer models of casting, welding and 3D printing of metals, and has led projects involving microgravity experiments in space (on alloy solidification). Prof. Browne is also carrying out research on bulk metallic glasses – a family of materials with very high strength and corrosion resistance, which can be made very flat (e.g. for optical applications) or nano-patterned in order to tailor interaction with other materials – liquid, solid or biological. During academic year 2019 to 2020 David was on sabbatical leave at Yale University, USA, working on research on formulation and processing of such amorphous alloys.
Research Interests (Lay Summary)
3D printing in metals involves aspects taken from more conventional manufacturing processes such as powder metallurgy, casting and welding. Prof. Browne uses his expertise to study phenomena which are already well understood in his research group, and adapts this for use in additive manufacturing. These include the sequential processes of melting and re-solidification of multiple layers of alloy which are a feature of most 3DP of metallic alloys. For example, in casting processes there are two main types of grain structure: columnar (preferable for aero-engine turbine blades) and equiaxed (good for hip or knee replacement parts). Control of alloy chemistry and solidification conditions determine which of these two types of microstructure is achieved in castings, but also in welded joints and in additively manufactured products. The solidification/thermal conditions also largely control defect formation in 3DP, and if not optimised can lead to porosity, residual stresses and hot or cold cracking. Browne’s team is using a combination of advanced numerical modelling and experimentation to solve some of these additive manufacturing problems in I-Form.