About

Professor Michael E. McHenry is a Professor of Materials Science and Engineering at Carnegie Mellon University, with courtesy appointments in Biomedical Engineering and Physics. He completed his B.S. in Materials Science and Engineering at Case Western Reserve University in 1980 and earned his Ph.D. in Electronic Materials from the Massachusetts Institute of Technology in 1988. Following his doctoral studies, he was a Directors Funded Post-Doctoral Associate at Los Alamos National Laboratory from 1988 to 1989. He joined Carnegie Mellon University in 1989 as an Assistant Professor and progressed to Associate Professor in 1992, becoming a full Professor in 1997. Prior to his academic career, he worked in the Technology Implementation Program at U.S. Steel - Lorain Works from 1980 to 1983. Professor McHenry's research focuses on magnetic materials, particularly amorphous and nanocrystalline materials for applications as soft magnets and nanocomposite alloy design for power electronic applications. He has made significant contributions to the understanding of magnetic properties of metals and alloys, and his work has been widely recognized and cited in the field. He has authored a textbook titled "Structure of Materials," published by Cambridge University Press, with a second edition released in 2012. His research excellence has been honored with the 2014 TMS Award for Research Excellence in Electronic, Magnetic and Photonic Materials Research. In addition to his research, Professor McHenry has been actively involved in the scientific community, serving in various roles for the MMM and Intermag Conferences for over 20 years, including session chair, program committee member, editor, publication chair, and co-Chair of the 2014 Intermag Conference in Dresden, Germany. He was also a 2013 IEEE Distinguished Lecturer, delivering lectures worldwide on nanocomposite alloy design. He has mentored numerous graduate students and post-doctoral associates, contributing to the development of future leaders in materials science.

Research topics

• Metallurgy
• Chemical engineering
• Crystallography
• Materials science
• Nanotechnology
• Composite material
• Chemistry
• Thermodynamics

Selected publications

• Optimization Study of Rare Earth-Free Metal Amorphous Nanocomposite Axial Flux-Switching Permanent Magnet Motor

  Energies · 2025-01-30

  articleOpen access

  Metal amorphous nanocomposite (MANC) soft magnetic materials exhibit remarkably low iron loss and high saturation magnetization. However, they have not been widely used in electric motors largely due to a lack of demonstrated manufacturing processing methods and an absence of proven motor designs well suited for their use. Recent developments in these two areas have prompted the optimization study of flux-switching with permanent magnet motor topology using MANCs presented here. This study uses population-based optimization in conjunction with a simplified electromagnetics model to seek rare earth-free designs that attain or exceed the state of the art in power density and efficiency. To predict the maximum mechanically safe rotational speed for each design with minimal computational effort, a new method of quantifying the rotor assembly mechanical limit is presented. The resulting population of designs includes motor designs with a specific power of up to 6.1 kW/kg and efficiency of up to 99% without the use of rare earth permanent magnets. These designs, while exhibiting drawbacks of high electrical frequency and significant manufacturing complexity, exceed the typical power density of representative state-of-the-art EV motors while increasing efficiency and eliminating rare earth elements.

  PublisherDOI

• Evaluation of Rotational Speed Limits in an Axial Flux-Switching Motor Constructed From Metal Amorphous Nanocomposite Magnetic Cores

  IEEE Transactions on Energy Conversion · 2024-04-25 · 4 citations

  article

  Given the promising high frequency magnetic properties of metal amorphous nanocomposite (MANC) soft magnetic materials (SMMs), recent efforts seek to use MANCs in electric motors to achieve high specific power utilizing elevated magnetic frequency. Such motors can operate at high rotational speed, as eddy current losses pose less limitations on their performance. It is thus important to understand mechanical stress distributions in a motor constructed from MANCs and to predict the likelihood of failure for such a machine at high speeds. Here, we model the residual stress due to the manufacturing process and the operating rotational stress of a MANC rotor. Previously reported failure distributions of laminated MANC ribbons are then used in conjunction with stress results to predict MANC motor failure rates. Because of brittle MANC failure, a design philosophy based on statistics rather than factor of safety (FOS) is used for a range of rotational speeds in our axial motor design. We estimate the probability of failure in a proof test as a function of operational speed. For our design, we determine that a failure rate of 1 in 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup> at an operational speed of 12.5 kRPM can be achieved for a 45.8 kW motor.

  PublisherDOI

• A Magnetic Soft Device for Tactile Haptic Actuation of the Fingertip

  2023-07-10 · 5 citations

  article

  In this work, we introduce a novel haptic device composed of a wearable fingertip sheath, fabricated using an oleogel loaded with magnetic particles, and an external electromagnet. The sheath is actuated using the external magnetic field provided by the electromagnet, which is equipped with a field-focusing pole piece. The oleogel composite used in this device has been optimized for the transfer of the magnetic force from the material to the skin to provide perceptible forces to the wearer. We compare our composite to composites created with materials commonly used in the literature and find the force transfer from our material, as measured by a force sensor, to be much greater when actuated under the same range of input voltages to the electromagnet. We also present a psychophysical user study that shows a linear relationship between this range of input voltages and perceptual magnitude. This result indicates that the device provides a range of tactile feedback that can be driven to a desired intensity of sensation through proportional voltage control.

  PublisherDOI

• Magnetic Anisotropy and Stress-Dependent Epoxy Wetting in FeNi-Based Metal Amorphous Nanocomposites

  IEEE Transactions on Magnetics · 2023-06-09 · 2 citations

  articleSenior author

  Recently developed FeNi-based metal amorphous nanocomposites (MANCs) used in high-speed motors (HSMs) exhibit reduced eddy current losses while maintaining good mechanical properties and glass-forming abilities. Magnetic anisotropy in (Fe70Ni30)80Nb4B14Si2 amorphous magnetic ribbon (AMR) in the as-cast state and upon conventional (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$T_{\mathrm {CA}}$ </tex-math></inline-formula>) and strain (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$T_{\mathrm {SA}}$ </tex-math></inline-formula>) annealing heat treatment is investigated. From ribbon samples in as-cast condition, quenched in stress from planar flow casting (PFC) induced as-cast curvature derived uniaxial magnetic anisotropy. Stress relief by conventional furnace annealing at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$T_{\mathrm {CA}} &gt;$ </tex-math></inline-formula> 350 °C achieved isotropic properties in the bulk. Annealing about the primary crystallization temperature, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$T_{\mathrm {CA}} \sim $ </tex-math></inline-formula> 450 °C, resulted in the formation of both face-centered cubic (FCC) and body-centered cubic (BCC) nanocrystallites and evolution to isotropic bulk magnetic properties confirming the random anisotropy model. In samples strain annealed at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$T_{\mathrm {SA}}$ </tex-math></inline-formula> = 440 °C at various tensions, relatively large controlled induced uniaxial anisotropy is achieved. The largest magnetic anisotropy occurs in annealing under the stress of 250 MPa yielding an anisotropy field of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$7.1\times 10^{4}$ </tex-math></inline-formula> A/m. Surface anisotropy observed by the magneto-optical Kerr effect (MOKE) differs from bulk anisotropy due to image contrast from closure domains. Epoxy coatings are important for improved bonding, mechanical properties, and resistivity in tape-wound MANC cores for HSMs. Using a sessile droplet method, the equilibrium contact angle of an epoxy droplet on a tensile stress-annealed MANC exhibits stress-dependent surface energies. Anisotropic wetting in FeNi-based MANC heat treated at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$T_{\mathrm {CA}}$ </tex-math></inline-formula> = 440 °C mimics surface magnetic anisotropy observed by MOKE.

  PublisherDOI

• Strength distributions of laminated FeNi-based metal amorphous nanocomposite ribbons

  Journal of Composite Materials · 2023-03-07 · 4 citations

  articleOpen access

  Metal Amorphous Nanocomposite (MANC) materials offer low losses at high magnetic switching frequency, enabling high power density motors with increased rotational speed. While MANCs have high strength, they are brittle. The use of motor components such as a rotor consisting of brittle material presents a reliability concern. Here, a promising MANC alloy is subjected to tensile tests and failure is observed with high-speed photography. A method is developed to prepare tensile specimens of laminated MANC and epoxy layers, simulating the stacking of an epoxy-impregnated tape-wound core. Tensile tests are conducted for single layer ribbon and for five- and ten-layer stacks of laminated material with thin layers of thermosetting epoxy. Failure distributions are shown to have increasing Weibull modulus with increasing layer count. The composite MANC material system is modeled using chain-of-bundles models. Using a k-failure model, we show that single ribbon strength distribution data can be used to predict well the failure distribution of laminated stacks. The agreement occurs when the assumed ineffective length, over which load is recovered in a failed layer, is comparable to the observed interlaminar separation length.

  PublisherOA PDFDOI

• Investigation of metal amorphous nanocomposite soft magnetic alloys in the (FexNiyCo100−x-y)80B14Nb4Si2 system

  Journal of Alloys and Compounds · 2023-03-12 · 1 citations

  articleOpen accessSenior author

  Following reports of attractive soft magnetic performance of an (Fe70Ni30)80B14Nb4Si2 alloy [1], [2], [3], improvement to this alloy is sought through substitution of small percentages of Co for Fe and/or Ni. Fifteen alloys in the (FexNiyCo100−x-y)80B14Nb4Si2 alloy system are fabricated by small batch planar flow casting and analyzed for various properties relating to their soft magnetic performance. Alloys synthesized are within the range x = 60–70 and y = 20–30. The most important properties studied here are saturation induction (Bsat), coercivity (Hc), saturation magnetostriction (λs), and Curie temperature (Tc). These metrics are important to various aspects of electric motor design. High Tc improves a material’s magnetic performance at elevated temperature, while lower Hc and λs reduce switching losses and larger Bsat is associated with higher torque capability. The resulting alloys have improved amorphous phase Tc of up to 414 ℃ and a λs reduction of up to 40%. This is achieved while keeping Hc of many compositions below 10 A/m and a calculated Bsat at T= 0 K of one alloy over 1.5 T. Given their improvements in the relevant properties, these new alloys present promise as soft magnets for electric motor applications.

  PublisherDOI

• Amorphous Metal Ribbon (AMR) and Metal Amorphous Nanocomposite (MANC) Materials Enabled High Power Density Vehicle Motor Applications (Final Technical Report)

  2023-03-31

  reportOpen access1st authorCorresponding

  A collaborative team from Carnegie Mellon Univ. (CMU), North Carolina State Univ. (NCSU) and Metglas, South Carolina have studied new high speed motors (HSMs) with high-power density for traction motor applications. These are enabled by hybrid designs, including Flux Switching with Permanent Magnets (FSWPM) motors, exploiting permanent magnets without heavy rare earths (RE-lean) and high induction/high resistivity soft magnetic materials that allow for high switching frequencies needed to increase power densities. Team members include Michael E. McHenry, Prof. Materials Science & Eng., CMU, with > 30 years experience in magnetic materials development; Subashish Bhattacharya, Prof. Electrical Eng. and Freedom Center Director at NCSU with > 30 years experience in development of power electronic components and systems and Eric Theisen, Director of Research at Metglas, the only US located supplier of AMR and MANC materials. The team offers novel axial motor architectures exploiting soft magnetic materials (SMMs) that switch with low loss at high frequencies and heavy rare earth free permanent magnets that address materials criticality issues, supply chain risks, and high costs for traction motors. Axial-flux permanent magnet motors (APFM), offer efficiency improvements reducing rotor losses and also significantly higher power density. Axial-flux construction requires less core material, high torque-to-weight ratio. Since AFPM machines have thin magnets, they are smaller than radial flux motors making them attractive in space-limited applications. Noise and vibration are less and planar air gaps are easily adjusted. Flexibility in air-gap direction allows many topologies.

  PublisherOA PDFDOI

• Analysis of surface roughness and oxidation of FeNi-based metal amorphous nanocomposite alloys

  Journal of Alloys and Compounds · 2022 · 22 citations

  Senior authorCorresponding
  • Materials science
  • Chemical engineering
  • Composite material

  We report on a systematic investigation of newly developed (Fe70Ni30)80Nb4B14Si2 metal amorphous nanocomposites (MANCs) and the factors affecting their surface roughness, including oxide formation and phase evolution during the nanocrystallization process. Analysis of surface roughness using atomic force microscopy (AFM) revealed an average roughness of 9.33 nm after heat treatment compared with as-cast amorphous ribbons, which exhibited a roughness of 4.21 nm. A surface oxide layer thickness has been determined using X-ray photoelectron spectroscopy (XPS). For samples annealed at 400 °C for 1 h, 450 °C for 1 h, and 550 °C for 3 h in air, the average surface oxide layer thickness was determined to be 10.9, 11.7, and 54.4 nm, respectively. It was observed that oxygen is enriched at the outermost surface and decreases rapidly as the XPS sputtering depth increases. Fe-oxide appeared as a predominant metal oxide at the top surface, followed by the presence of Nb oxide. A boron content increase was observed at the interface between the top surface oxide layer and the bulk of the sample. A protective surface oxide layer on FeNi-MANCs, such as observed in this work, can provide sufficient electrical insulation to reduce interlaminate eddy current losses and lower overall losses in magnetic components.

  PublisherDOI

• Radio‐Frequency Rapid Thermal Processing Enabling Spatial Phase Transformation and Nanocrystallization of Soft Magnetic Amorphous Alloys

  Advanced Engineering Materials · 2022-05-12 · 6 citations

  articleOpen access

  Thermal processing of soft magnetic amorphous and nanocrystalline alloys is explored under the influence of radio‐frequency induction‐heating techniques. Direct induction‐heating concepts based on longitudinal and transverse flux heating are examined and the details of electromagnetic fields interaction with metallic strips are discussed by analytical calculations as well as finite element analysis. Initial experimental results confirming spatial control of phase transformations and nanocrystallization within a single strip of Finemet Fe‐based amorphous ribbons are reported. The degree to which primary and secondary crystallization temperature are achieved depends on the spacing between the ribbon relative to the induction coil as well as the coil design and configuration. For transverse coil configurations, the local temperature and therefore microstructural evolution is different across the lateral dimension of processed ribbons, with reduced gap sizes producing enhanced peak temperatures and larger temperature distributions with greater spatial variation in microstructure. In addition, indirect susceptor‐based induction heating under tension is performed and the impact of microstructure is demonstrated. Herein, potential for exploiting spatially optimized phase transformations is illustrated through electromagnetic field–assisted processing in a scalable manufacturing process with amorphous and nanocrystalline soft magnetic alloys.

  PublisherOA PDFDOI

• Investigation of Metal Amorphous Nanocomposite Soft Magnetic Alloys in the (Fexniyco100-X-Y)80b14nb4si2 System

  SSRN Electronic Journal · 2022-01-01

  articleOpen accessSenior author
  PublisherDOI

Recent grants

• Magnetocaloric Effect in Alloys with Distributed Exchange Interactions

  NSF · $473k · 2017–2021

• Nanostructural Evolution and Magnetic Response in the Oxidation of FeCo Nanomaterials

  NSF · $804k · 2008–2016

• Nanocrystallization Kinetics and Induced Anisotropy in Soft Magnetic Nanocomposites

  NSF · $512k · 2004–2008

• Materials World Network: Titanomagnetite Decomposition and Magnetic Sensors for Their Terrestrial and Extraterrestrial Observation.

  NSF · $588k · 2011–2016

Frequent coauthors

• David E. Laughlin

  77 shared

• Paul R. Ohodnicki

  University of Pittsburgh

  62 shared

• Marc De Graef

  Carnegie Mellon University

  37 shared

• Vladimir Keylin

  34 shared

• A Kuznetsov

  Kuzbass State Technical University

  32 shared

• Alex Leary

  Glenn Research Center

  31 shared

• Marina Díaz-Michelena

  27 shared

• J. M. MacLaren

  Tulane University

  24 shared

Labs

• Mike McHenry LabPI

Education

• Ph.D., Materials Science and Engineering

  Massachusetts Institute of Technology

  1988

• B.S., Metallurgical Engineering and Materials Science

  Case Western Reserve University

  1980

• Other, Superconducting Materials

  Los Alamos National Laboratory

  1989

Awards & honors

• 2013 IEEE Distinguished Lecturer
• 2014 TMS Awardee for Research Excellence in Electronic, Magn…
• 2016 TMS Symposium in Honor of M. E. McHenry
• 2016/17 NATO Series Lecturer on Rare Earth Criticality