Ian Baker

Sherman Fairchild Professor of Engineering

Senior Associate Dean, Research and Graduate Programs

Baker discusses his research, focusing on the properties and the mechanical and magnetic behavior of materials, and how this work can help power plants be much more energy efficient.

Research Interests

Materials for energy systems; mechanical behavior; phase tranformations; electron microscopy; x-ray topography; x-ray diffraction; microstructure and mechanical behavior of snow, firn, and ice; magnetic materials; intermetallic compounds; high entropy alloys; high temperature materials; nanoparticles for magnetic hyperthermia; biomaterials

Education

BA, Metallurgy and Science of Materials, University of Oxford 1979
D.Phil, Metallurgy and Science of Materials, University of Oxford 1982

Awards

2015 Fellow, American Association for the Advancement of Science (AAAS)
2012 Fellow, Minerals, Metals & Materials Society (TMS)
2011 Fellow, Materials Research Society
2003 Listed in ISI citation index of highly-cited Materials Scientists
2002 Fellow, The Institute of Materials, Minerals and Mining (U.K.)
2001 Fellow, ASM international
1993 Chartered Engineer (C.Eng.) of The Engineering Council (U.K.)

Professional Activities

Field-Chief-Editor, Frontiers in Metals and Alloys (2022–)
Co-Editor-in-Chief, High Entropy Alloys & Materials (2022–)
Organizer, Physics and Chemistry of Ice, Dartmouth (2014)
Organizer, MRS Fall Meeting Symposium on Intermetallic-based Alloys — Science, Technology, and Applications (2014)
Editorial Board, Nano Life (2009–)
Editorial Advisory Board, Intermetallics (1998–)
Editorial Board, Metals (2010–)
Editor in Chief, Materials Characterization (2009–2020)
Editorial Board, International Materials Reviews (2002–2020)
Reviewer for various US, Canadian, Hong Kong, Swiss, French, and Australian government agencies and numerous journals
Consultant to various companies on microstructural characterization and materials processing
Editor of the proceedings of five conferences

Research Projects

Transmission electron microscope studies of high entropy alloy catalysts

Transmission electron microscope studies of high entropy alloy catalysts

Understanding the behavior of high-entropy alloy (HEA) nanoparticles under relevant environments is essential to advancing their use in certain applications, namely catalysis. This project utilizes transmission electron microscopy to investigate HEA catalysts in high temperature conditions.
Using first principles calculations and electro-pulse annealing to design and manufacture low-cost permanent magnets

Using first principles calculations and electro-pulse annealing to design and manufacture low-cost permanent magnets

Demand for high-performance permanent magnets for motors is increasing rapidly for applications such as wind turbine generators and motors in both electric and hybrid cars. Samarium-Cobalt and Neodymium-Iron-Boron Rare Earth magnets are generally used for such challenging applications. While Rare Earth magnets are the best currently available permanent magnets, they are not without problems such as being brittle, suffering from thermal shock, and experiencing corrosion. Further, over 95% of Rare Earths are produced in China and there has been substantial price volatility. Finally, Rare Earth mining has been associated with severe environmental degradation and large energy usage. NiFe, which has been identified in meteorites as the compound Tetrataenite where it transformed from the high temperature (disordered) f.c.c. phase over thousands of years, has magnetic properties comparable to that of Rare Earth magnets. This research award develops new, low-cost, environmentally-friendly NiFe-based permanent magnets, using both quantum-mechanical calculations to predict the effects of alloying with other elements coupled with experiments to verify the effects of these additional elements on the transformation kinetics and magnetic properties. It uses the novel approach of pulsed electrical heating, which has been shown to accelerate transformations. Both women and under-represented minorities will be engaged in the research. The development of novel NiFe magnets will enable production of permanent magnets to be relocated to the USA. As part of the work, the project develops a web site that offers simple virtual experiments to explain to a wide audience magnetism and the materials science of permanent magnets.

The L1₀-structured compound Nickel-Iron (NiFe) has the potential to replace Rare Earth (RE) magnets at low cost: NiFe has a magnetic anisotropy energy, k_u, of 1.3 x 10⁶ J.m^-3 and a saturation magnetization m₀M_S of 1.59 Tesla, which is comparable to that of Nd₂Fe₁₄B. In addition, it has good corrosion resistance. The challenge is that the binary L1₀ compound has a very low transformation temperature from the high-temperature f.c.c. phase of about 320^oC that forms on casting and, thus, orders very slowly at temperatures where it is stable. This project combines ab initio quantum mechanical calculations and experimental work to design new L1₀-structured NiFe magnets with ternary elemental additions. These ternary compounds potentially have a significantly higher f.c.c.-to-L1₀ transformation temperatures and higher diffusivities than binary NiFe, but have similar saturation magnetizations. Thus, the L1₀phase can be produced at higher temperature in short, commercially-viable times utilizing electro-pulse annealing of cold-worked material, which has also been shown to dramatically accelerate recrystallization in NiFe. The TEM-based technique ALCHEMI is used to determine the atom site locations of these ternary additions in the L1₀unit cell. This work demonstrates a practical paradigm for designing magnets and leads to new commercially-viable permanent magnet. Commercially, NiFe can be manufactured by continuous electro-pulse annealing of rolls of sheet material or of rods. NiFe is very ductile and can easily be machined into various shapes.
High-strength, high-ductility, high entropy alloys with high-efficiency native oxide solar absorbers for concentrated solar power systems

High-strength, high-ductility, high entropy alloys with high-efficiency native oxide solar absorbers for concentrated solar power systems

This project is investigating the synergy between the excellent mechanical behavior of FeMnNiAlCr high entropy alloys (HEAs) and the high solar absorptance of their native thermal oxides for high efficiency concentrated solar thermal power (CSP) systems working at >700^oC. The alloy itself would be used in high-temperature tubing to carry molten salts or supercritical carbon dioxide (sCO2), while the native oxide would act as a high-efficiency solar thermal absorber. The oxide layer is also dense and protective against oxidation (parabolic growth kinetics) at 750 °C. This new Fe-Mn based HEA system has already demonstrated a higher tensile strength and ductility than more expensive Ni-based Inconel 740 superalloys at both room temperature (with carbon doping) and 750^oC (with Ti doping), and their native thermal oxides have achieved a high optical-to-thermal conversion efficiency of ηtherm=90.8% at 750°C under 1000x solar concentration ratio. In preliminary corrosion studies, two-phase Cr-modified HEAs have sustained bromide molten salts for 14 days at 750°C with <2% weight loss. The project has close collaborations with the Oak Ridge National Laboratory (ORNL) and the Ames Laboratory in computational materials science and atom probe tomography (APT) to understand the fundamental structure-property relationship in FeMnNiAlCr HEAs.

Funded by DOE.
New Hampshire Center for Multiscale Modeling and Manufacturing of Biomaterials (NH Bio-MADE)

New Hampshire Center for Multiscale Modeling and Manufacturing of Biomaterials (NH Bio-MADE)

Orthopedic implants are often required to replace or support damaged skeletal structures. For this application and many others, an individualized component, determined, through, for example, an MRI scan, is required for repairs. Thus, the ability to rapid prototype biomedical implants for mass customization is desirable. Furthermore, the final product properties and characteristics are critical to, for example, reduce the gauge thickness and, thus, the weight of the component. Computational modeling is necessary to optimize the final product. Cost is important so creating the component from stock sheet metal, as opposed to from metal powder, machining from a large workpiece, or casting the component, is advantageous. Furthermore, by work hardening of the material through forming, increased strength is achieved.

With respect to sheet metal, characterizing the material behavior thoroughly is essential to produce an optimal final product. Tests to characterize the material, e.g. uniaxial tension/compression (Marciniak tests), are typically performed under proportional loading and follow a linear deformation path. Such testing can produce a failure criterion for the material, e.g., a forming limit curve (FLC), which represents the planar strain values in sheet metal above which the deformation localizes into a diffuse neck. The strain path dependence of FLCs has been documented by a number of workers. During forming, the deformation path can be intentionally manipulated to improve the forming process. For example, if a sharp corner feature is desired in a component, a generous radius is formed first, then a restrike operation is performed in the corner with the desired sharp punch tool. The variation in the deformation path allows the final strain values to be below the FLC and, thus, avoids failure. While such industrial applications are well known, the phenomenon which allows this increased formability during non-linear deformation path loading is poorly understood. This project will test the hypothesis that the increased formability exhibited by metallic alloys during non-linear deformation paths results from dislocation mechanisms, i.e., recombination and change of glide systems upon strain-path change, which prevents strain localizations due to pile-ups at grain or phase boundaries or other interfaces in the microstructure. Increment forming of stainless steel and titanium parts is being performed at the University of New Hampshire alongside numerical modeling of the process, while analysis of the dislocation structures using transmission electron microscopy and scanning electron microscopy is being performed at Dartmouth.

Funded by the U.S. National Science Foundation EPSCOR program.
ECAE processing of Tau-MnAl magnets

ECAE processing of Tau-MnAl magnets

Demand for high-performance permanent magnets is increasing rapidly for applications such as wind turbine generators and motors in both electric and hybrid cars. This market is served by rare earth (RE) magnets based on Nd2Fe14B and Sm2Co17. RE magnets are not without issues; they can chip, suffer thermal shock, and can suffer grain boundary corrosion. However, their biggest problems are: price volatility; that China largely controls the RE metals market; and that the extraction of RE metals creates severe environmental degradation. L10-structured Tau-MnAl has been of interest as a permanent magnet since the early 1960s. It has a theoretical energy product, (BH)max, between that of AlNiCo magnets and RE magnets with a value (12 MGOe) comparable to that of bonded Nd2Fe14B magnets. Further, it does not suffer from the issues associated with RE magnets, and potentially has the lowest cost per MGOe of any permanent magnet. The enigma is that the theoretical (BH)max has never been achieved: mechanically-milled particulates can show high coercivity (HC) but low saturation magnetization (MS) while warm-extruded material can show high MS but low HC. Tau-MnAlis a metastable phase that transforms from the high temperature ε phase, during which anti-phase boundaries (APBs), twins, stacking faults and dislocations are created. Depending on the processing conditions, the equilibrium β and γ2phases can also form. The fundamental difficulty with improving the magnetic properties of Tau-MnAl is that there is no clear understanding on how they depend on the defect structure. The grain size can also influence the magnetic properties either directly or by affecting the β and γ2 arrangement and defect formation.

We are using equal channel angular extrusion (ECAE) to process Tau-MnAl billets over a range of temperatures. Multiple passes will be performed utilizing Routes A (extruded billet is fed back into the ECAE jig in the same orientation) and BC(extruded billet is rotated 90o clockwise about its axis between passes). We will determine the texture of the extruded billets, and the density and arrangement of APBs, twins, stacking faults, dislocations and second phases after each pass, and relate these to the magnetic properties. The local chemistry will be explored at high resolution using atom probe tomography via collaboration with Dr. Baptiste Gault, Max-Planck-Institut fur Eisenforschung, Germany. To extend the strain range and, hence, defect densities studied we will also explore using severe plastic deformation through a collaboration with Prof. Gheoghe Gurau, University of Galati, Romania. Our working hypothesis is that we need a strong, c-axis alignment and a low density of APBs, twins and stacking faults (which locally disorder the material) for a high MS, while a low density of APBs, twins and stacking faults but a high dislocation density are required for a high HC. It is thought that a fine distribution of β and γ2 phases will also contribute to a high HC through magnetic domain wall pinning.

Funded by the National Science Foundation.
The impact of impurities and stress state on polycrystalline ice deformation
The impact of impurities and stress state on polycrystalline ice deformation
Despite the ubiquitous use of the constitutive relation for ice commonly referred to as “Glen’s Flow Law,” significant uncertainty exists particularly with regard to the role of impurities and the development of oriented fabrics. The aim of this project is to improve the constitutive relationship for ice by performing deformation tests and microstructural characterization of pure and sulfuric acid-doped ice. The research proposed here will focus on sulfuric acid’s impact on ice viscosity, fabric evolution, and diffusivity. Sulfuric acid can have both direct—by changing the dislocation velocity and/or density—and indirect—by changing the grain size and fabric—effects on the mechanical properties of polycrystalline ice. The complexity and interaction of these effects means that one cannot understand the effects of sulfuric acid by simply examining ice core specimens.

In this project, we will deform four types of ice:
1. lab-grown ice samples doped with similar-to-natural concentrations of sulfuric acid,
2. lab-grown high-purity ice,
3. layered doped and pure ice, and
4. natural ice from Antarctic ice cores.
Deformation will be performed in both uniaxial compression and simple shear. The addition of simple shear tests is critical for relating the laboratory-observed deformation behavior to the behavior of polar ice sheets where the shear strain dominates ice motion in basal ice. After deformation to strains from 5% up to 25%, the microstructural development will be assessed with state-of-the-art methods including a variety of scanning electron microscope techniques, Raman microscopy, synchrotron-based Nano-X-ray fluorescence and ion chromatography.

These analysis techniques will allow the determination of:
1. the segregation and movement of impurities;
2. the rate of grain boundary migration;
3. the number of recrystallized grains; and
4. the full orientation of the ice crystals.
The results will enable both microstructural modeling of the effects of H2SO4 and numerical modeling of diffusion in ice cores. The net result will be a better understanding of ice deformation that improves ice-core interpretation and ice-sheet modeling. The work will lead to the education of a PhD student at Dartmouth, introduce undergraduate students to research at both the University of Washington and Dartmouth, and bring together the microstructural expertise of Dartmouth with the ice-core measurement and modeling emphasis at the University of Washington.

Funded by the US National Science Foundation
Porous thermoelectric cells (TECs) for waste heat recovery

Porous thermoelectric cells (TECs) for waste heat recovery

Porous thermoelectric cells (TECs) are being developed for waste heat recovery. This project seeks to convert waste thermal energy directly into electricity potentially increasing overall energy efficiency by 15-20% and providing new portable electric power sources, particularly for cold regions. The project is focusing on low cost, nanostructure-engineered TEC (NETECs) materials based on earth-abundant, highly machinable metallic alloys and intermetallic compounds by engineering the grain sizes, second phase precipitation, and nanopores in transition metal intermetallic compounds. The project is currently focusing on the compound Fe2AlV. The location of quaternary atoms in the lattice is being determined by the TEM-based technique ALCHEMI.

Funded by USA-CRREL

Selected Publications

"Dynamic observations of the densification of polar firn under compression using a Micro-Computed Tomograph," Yuan Li and Ian Baker, Journal of Geophysical Research — Earth Surface, 126 (2021) e2021JF006290. https://doi.org/10.1029/2021JF006290
"Strengthening and toughening B₄C/Al composites via optimizing the Al₂O₃distribution during hot rolling," Hao Guo, Junpeng Li, Naimeng Liu, Xinghao Wei, Mingyu Fan, Yongxuan Shang, Wenqing Jiang, Yang Zhang, Ye Cui, Lixin Sun, Ian Baker and Zhongwu Zhang, Journal of Alloys and Compounds, 902 (2022) 163773 (15 pages). https://doi.org/10.1016/j.jallcom.2022.163773
"The effect of Al/Ti ratio on the evolution of precipitates and their effects on mechanical properties for Ni₃₅(CoCrFe)₅₅Al_xTi_10-x high entropy alloys," Liyuan Liu, Yang Zhang, Guangchuan Wu, Yongzheng Yu, Yaxi Ma, Jingming Ma, Ian Baker and Zhongwu Zhang, Journal of Alloys and Compounds, 906 (2022) 164291. https://doi.org/10.1016/j.jallcom.2022.164291
"Phase transformation via atomic-scale periodic interfacial energy," Y. Cui, Y. Zhang, L. Sun, M. Feygenson, X.-L. Wang, P.K. Liaw , I. Baker and Z. Zhang, Materials Today Physics, 24 (2022) 100668. https://doi.org/10.1016/j.mtphys.2022.100668
"Interstitial Strengthening in f.c.c. Metals and Alloys," I. Baker, Advanced Powder Materials, 1 (2022) 100034. https://doi.org/10.1016/j.apmate.2022.100034
"Development of a new cryogenic tribotester and its application to the study of cryogenic wear of AISI 316 stainless steel," Francis E. Kennedy, Youxiong Ye, Ian Baker, Raina R. White, Robert Barry and Min Song, Wear, 496–497 (2022) 204309. https://doi.org/10.1016/j.wear.2022.204309
"Simultaneous Twinning and Microband-Induced Plasticity of a Compositionally Complex Alloy with Interstitial Carbon at Cryogenic Temperatures," A.S. Tirunilai, R. Osmundsen, I. Baker, H. Chen, K.‐P. Weiss, M. Heilmaier and A. Kauffmann, High Entropy Alloys & Materials (2022). https://doi.org/10.1007/s44210-022-00001-9
"Microstructure, Mechanical Properties and Biocompatibility of Laser Metal Deposited Ti-23Nb Coatings on a NiTi Substrate," Y. Ren, J. Du, B. Liu, Y. Tian, I. Baker and H. Wu, Materials Science and Engineering, A 848 (2022) 143402. https://doi.org/10.1016/j.msea.2022.143402
"Microstructures and deformation mechanisms of the medium-entropy alloy(CoCrNi)₉₄Al₃Ti_3," Hanlin Peng, Ling Hu, Junfu Chen, Siming Huang, Liejun Li, Yaoyong Yi, Feng Zhou, Weiping Fang and Ian Baker, Materials Science and Engineering A, 849 (2022) 143449. https://doi.org/10.1016/j.msea.2022.143449
"A comparative study on microstructure, nanomechanical and corrosion behaviors of AlCoCuFeNi high entropy alloys fabricated by selective laser melting and laser metal deposition," Yaojia Ren, Hong Wu, Bin Liu, Yong Liu, Sheng Guo, Z.B. Jiao and Ian Baker, Journal of Materials Science & Technology, 131 (2022) 221–230. https://doi.org/10.1016/j.jmst.2022.05.035

Patents

Oxidation resistant high-entropy alloys | 10,190,197
Nanostructured Mn-Al permanent magnets and methods of producing same | 8,999,233
Joining of parts via magnetic heating of metal aluminum powders | 8,444,045
Joining of parts via magnetic heating of metal-aluminum powders | 8,172,126
System and method for use of nanoparticles in imaging and temperature measurement | 7,994,786
High-strength nanostructured alloys | 7,815,850