CAREER: Heterogeneous Nucleation in Reversible Martensitic Transformations – NSF
Senior Personnel: P. Shamberger (PI)
Martensitic transformations are reversible transitions involving a diffusionless distortion of the lattice. The result of cycling martensitic materials is a change in the shape and properties of a material. This behavior leads to the development of miniaturized and efficient actuators, sensors, and various microelectronic devices. These structural transformations start near a defect or imperfection in a material, facilitating the formation of martensitic nuclei. However, when considering transformations in small volumes of material, the probability of encountering such a rare defect is low, resulting in unpredictable and inefficient operation. This project aims to understand how defects initiate transformations while introducing approaches to induce such defects into a material. These aims would allow the efficient operation of devices at micrometer and nanometer length scales.
We are interested on two types of defects and their potency to initiate martensitic nucleation. The first type of defect is the effect of L21 domain interfacial area densities formed by secondary annealing at 773 K and solution heat treatment. The second type of defect is Frenkel-pairs created by He+ ion irradiation at 2 MeV and small doses of 0.002 DPA. Literature shows well-developed dislocation defect models of heterogeneous nucleation in martensitic transformations. However, the role of clusters of point defects and order-disorder interfaces is poorly understood. Understanding what types of defects can initiate nucleation is important to reduce degrees of undercooling and thermal hysteresis in phase transformations. The outcomes of this study will advance the science of martensitic nucleation by measuring the number density of native nucleation sites as a function of the thermodynamic driving force and by experimentally quantifying the potency of various defects.
- S. Chakravarty*, D.J. Sharar, P.J. Shamberger. Heterogeneous Nucleation of Gallium with Lattice-Matched Cubic Carbide and Nitride Phases, J. Appl. Phys, 130, 125107 (2021). doi: 10.1063/5.0060207.
- Y. Zhang*, C. Lago*, I. Karaman, P.J. Shamberger. Nucleation site potency distributions in thermoelastic martensitic transformation in Ni43Co7Mn39Sn11 particles, Phys. Rev. Mater., 5(2), 023401 (2021). doi: 10.1103/PhysRevMaterials.5.023401
- A. Yano*, H. Clarke*, D. Sellers, E.J. Braham, T.E.G. Alivio, S. Banerjee, P.J. Shamberger. Towards High-Precision Control of Transformation Characteristics in VO2 through Dopant Modulation of Hysteresis, J. Phys. Chem. C., 124(39), 21223-21231 (2020). doi: 10.1021/acs.jpcc.0c04952
- Clarke, H.*, B. Carraway#, D. Sellers, E. Braham, S. Banerjee, R. Arróyave, P.J. Shamberger. Nucleation-controlled hysteresis in unstrained hydrothermal VO2 particles, Phys. Rev. Materials, 2, 103402 (2018) doi: 10.1103/PhysRevMaterials.2.103402
- Shamberger, P.J., M. O’Malley. Heterogeneous Nucleation of Thermal Storage Material LiNO3•3H2O from Stable Lattice-Matched Nucleation Catalysts, Acta Materialia, 84, 265-274 (2015). doi: 10.1016/j.actamat.2014.10.051