Colloquium: Physics & Astronomy – Dr. Gary Collins

About the event

The Department of Physics and Astronomy invites all to a colloquium featuring Dr. Gary Collins, Department of Physics and Astronomy and Washington State University. Dr. Collins will present his talk, “Solubility and partition of solute between sublattices in an intermetallic compound”.

Meet for refreshments before the lecture at 3:45 – 4:10 p.m. in the foyer on floor G above the lecture hall.

While solutes may have a strong preference to occupy just one sublattice in an ordered phase, they often distribute among multiple sublattices. An interesting question is how solute atoms partition among sublattices as a function of temperature, host alloy composition, and mole fraction of solute.

Early experiments showed that extremely dilute mole fractions of indium solute (about 10-9) dissolved on both sublattices in Laves phase GdAl2, with solutes preferring the Gd-sublattice at low temperature and Al-sublattice at high temperature, with a transfer enthalpy of 0.343 eV.[1] New experiments show that solute transfer gets “blocked” as indium solute mole fraction increases up to ~0.5 atomic %. It will be shown how this blocking phenomenon depends on phase boundaries of the pure host alloy and the solute mole fraction. In effect, there is competition between solute atoms and intrinsic defects such as antisite atoms to occupy a fixed number of available sites on each sublattice. The results give broad insight into behavior of technologically important phases, many of which have ~1 atomic % of dissolved solute.

* With Ryan Murray, PhD 2017, and partial support from National Scence Foundation grant DMR 14-10159. [1] Matthew O. Zacate and Gary S. Collins, Phys. Rev. B69, 174202 (2004).