Boettinger photo

Bill Boettinger

Dr. William J. Boettinger, NAE
NIST Fellow
Metallurgy Division
Materials Science and Engineering Laboratory
Gaithersburg, MD 20899

Research Interests

Phase-Field Calculations

Solidification work has been done in collaboration with Jim Warren in the Metallurgy Division and Jeff McFadden in the Center for Computational & Applied Mathematics at NIST, as well as Adam Wheeler at the University of Southhampton (U.K.) This model differs from more traditional approaches to solidification, in that the liquid-solid interface is assumed to be diffuse. This permits simulation of solidification pattern without "tracking" the position of the liquid-solid interface. Work on solute trapping has also been completed.

Click on the Figure below to see movies (phase-field simulations) of Nickel-Copper solidification done in collaboration with Jim Warren.

Solidification calculation

The Phase-Field approach has also been applied to modeling the equilibrium and dynamics of planar electrochemical interfaces. This work has been done in collaboration with with Jon Guyer of the Electrochemical Processing Group of the NIST Metallurgy Division.    Equilibrium  Kinetics  Animated graph (concentrations, charge and potential) during initial transient and steady state alloy plating

Solder and Solder Finishes

Phase diagrams of selected Pb-free solder systems are under investigation (click here). The location of the ternaty eutectic in Sn-Ag-Cu alloys has been determined. See "Experimental and Thermodynamic Assessment of Sn-Ag-Cu Solder Alloys,” K.-W. Moon, W. J. Boettinger, U. R. Kattner, F. S. Biancaniello and C. A. Handwerker, J. Electronic Materials, 29 (2000), pp. 1122 - 1136.

Soldering involves a reaction of Sn with the base metal being soldered. The diffusion processes involved in a simple reactive wetting problem disolution of the substrate only) were studied to determine how the triple junction motion is coupled to this reaction.  See "Modeling Reactive Wetting”, J. A. Warren, W. J. Boettinger & A. R. Roosen, Acta Mater., 46 (1998) 3247. Work is  contining use a phase fffield approach.

Sn whisker growth has become a reliability issue with the convesion to Pb-free surface finishes to maintain soldeability on electronic components.   Stresses in electrodeposited Sn has been measured with a cantilever beam technique with a focus on understanding the mechanisms of whisker growth. At paper on NIST whisker research is available  (click here). Current work involves measurement of stress in Sn electrodeposits  using x-ray diffraction

Solidification Path

Completed research with industry includes an effort to improve the modeling of castings through the NIST "Consortium on Casting of Aerospace Alloys." Efforts here were focussed on describing the solidification path for multicomponent Ni-base superalloys. This approach utilizes a thermodynamic calculation of the phase diagram information needed for the solidification kinetic models. Much of this work is described each May/June  at a Solidification course in Les Diablerets in Switzerland that is sponsored by EPFL (M. Rappaz).


To assist users of Differential Thermal Analysis understand the response of the instrument to the melting and freezing of alloys,  a MathematicaTM script & description of published work with Ursula Kattner  can be downloaded . A "Best Practice Guide" on the subject is completed. Click here.

Multicomponent/Multiphase Diffusion

Research has been focused on modeling transient liquid phase bonding (w/ Carelyn Campbell) of Ni-Al with Ni-B. The thermodynamics of the Ni-Al-B system has been developed using the Calphad method. The diffusion behavior has been modeled with the code, Dictra.  Three dimension effects encountered with the Kirkendall effect has been treated. See publication list. Click here to see the activities of the NIST Diffusion Working Group


Recent research with Albert Davydov of the NIST Metallurgy Division is focused assessing metal-semiconductor phase diagrams to provide rationale for selecting VLS growth catalysts and electrical contact metals for ZnO and GaN nanowires.

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