Robert O. Ritchie
University of California, Berkeley · Aerospace program
Active 1963–2024
About
Robert O. Ritchie is a Distinguished Professor of Mechanical Engineering and Professor of Materials Science & Engineering at UC Berkeley. His research focuses on the fracture and fatigue of materials, including metallic glasses, hypersonic materials, mineralized biological tissues, high-temperature alloys, and biomedical materials. He investigates mechanisms of fatigue and fracture in various materials, such as SiC at high temperatures, NiTi shape memory alloys for biomedical applications, and atomic-resolution studies of fracture in SiC. Professor Ritchie's work encompasses the study of grain boundary engineering to promote high-cycle fatigue resistance and the atomic-scale mechanisms of fracture in brittle materials. His contributions are recognized in the field of materials science and mechanical engineering, and he maintains an active research group, the Ritchie Group, with a comprehensive website detailing his publications and research activities.
Research topics
- Materials science
- Crystallography
- Nanotechnology
- Computer Science
- Composite material
- Mechanical engineering
- Chemical physics
- Manufacturing engineering
- Engineering
- Metallurgy
- Computational chemistry
- Physics
- Chemistry
- Thermodynamics
Selected publications
One dimensional wormhole corrosion in metals
Nature Communications · 2023 · 86 citations
- Materials science
- Chemical physics
- Metallurgy
Corrosion is a ubiquitous failure mode of materials. Often, the progression of localized corrosion is accompanied by the evolution of porosity in materials previously reported to be either three-dimensional or two-dimensional. However, using new tools and analysis techniques, we have realized that a more localized form of corrosion, which we call 1D wormhole corrosion, has previously been miscategorized in some situations. Using electron tomography, we show multiple examples of this 1D and percolating morphology. To understand the origin of this mechanism in a Ni-Cr alloy corroded by molten salt, we combined energy-filtered four-dimensional scanning transmission electron microscopy and ab initio density functional theory calculations to develop a vacancy mapping method with nanometer-resolution, identifying a remarkably high vacancy concentration in the diffusion-induced grain boundary migration zone, up to 100 times the equilibrium value at the melting point. Deciphering the origins of 1D corrosion is an important step towards designing structural materials with enhanced corrosion resistance.
Materials Science and Engineering R Reports · 2021 · 689 citations
- Computer Science
- Manufacturing engineering
- Computer Science
Additive manufacturing of industrially-relevant high-performance parts and products is today a reality, especially for metal additive manufacturing technologies. The design complexity that is now possible makes it particularly useful to improve product performance in a variety of applications. Metal additive manufacturing is especially well matured and is being used for production of end-use mission-critical parts. The next level of this development includes the use of intentionally designed porous metals - architected cellular or lattice structures. Cellular structures can be designed or tailored for specific mechanical or other performance characteristics and have numerous advantages due to their large surface area, low mass, regular repeated structure and open interconnected pore spaces. This is considered particularly useful for medical implants and for lightweight automotive and aerospace components, which are the main industry drivers at present. Architected cellular structures behave similar to open cell foams, which have found many other industrial applications to date, such as sandwich panels for impact absorption, radiators for thermal management, filters or catalyst materials, sound insulation, amongst others. The advantage of additively manufactured cellular structures is the precise control of the micro-architecture which becomes possible. The huge potential of these porous architected cellular materials manufactured by additive manufacturing is currently limited by concerns over their structural integrity. This is a valid concern, when considering the complexity of the manufacturing process, and the only recent maturation of metal additive manufacturing technologies. Many potential manufacturing errors can occur, which have so far resulted in a widely disparate set of results in the literature for these types of structures, with especially poor fatigue properties often found. These have improved over the years, matching the maturation and improvement of the metal additive manufacturing processes. As the causes of errors and effects of these on mechanical properties are now better understood, many of the underlying issues can be removed or mitigated. This makes additively manufactured cellular structures a highly valid option for disruptive new and improved industrial products. This review paper discusses the progress to date in the improvement of the fatigue performance of cellular structures manufactured by additive manufacturing, especially metal-based, providing insights and a glimpse to the future for fatigue-tolerant additively manufactured architected cellular materials.
Nacre toughening due to cooperative plastic deformation of stacks of co-oriented aragonite platelets
Communications Materials · 2020 · 54 citations
- Materials science
- Composite material
- Crystallography
Abstract Nacre’s structure-property relationships have been a source of inspiration for designing advanced functional materials with both high strength and toughness. These outstanding mechanical properties have been mostly attributed to the interplay between aragonite platelets and organic matrices in the typical brick-and-mortar structure. Here, we show that crystallographically co-oriented stacks of aragonite platelets, in both columnar and sheet nacre, define another hierarchical level that contributes to the toughening of nacre. By correlating piezo-Raman and micro-indentation results, we quantify the residual strain energy associated with strain hardening capacity. Our findings suggest that the aragonite stacks, with characteristic dimensions of around 20 µm, effectively store energy through cooperative plastic deformation. The existence of a larger length scale beyond the brick-and-mortar structure offers an opportunity for a more efficient implementation of biomimetic design.
Heterostructured materials: superior properties from hetero-zone interaction
Materials Research Letters · 2020 · 1051 citations
- Materials science
- Nanotechnology
- Crystallography
Heterostructured materials are an emerging class of materials with superior performances that are unattainable by their conventional homogeneous counterparts. They consist of heterogeneous zones with dramatic (>100%) variations in mechanical and/or physical properties. The interaction in these hetero-zones produces a synergistic effect where the integrated property exceeds the prediction by the rule-of-mixtures. The heterostructured materials field explores heterostructures to control defect distributions, long-range internal stresses, and nonlinear inter-zone interactions for unprecedented performances. This paper is aimed to provide perspectives on this novel field, describe the state-of-the-art of heterostructured materials, and identify and discuss key issues that deserve additional studies.
Frequent coauthors
- 154 shared
R.K. Nalla
- 121 shared
Jamie J. Kruzic
UNSW Sydney
- 106 shared
Elizabeth A. Zimmermann
McGill University
- 105 shared
Mark Asta
University of California, Berkeley
- 103 shared
Andrew M. Minor
University of California, Berkeley
- 102 shared
Bernd Gludovatz
UNSW Sydney
- 94 shared
K. T. Venkateswara Rao
Western University
- 70 shared
Björn Busse
University Medical Center Hamburg-Eppendorf
Education
- 1990
Ph.D., Mechanical Engineering
University of California, Berkeley
- 1986
M.S., Mechanical Engineering
University of California, Berkeley
- 1984
B.S., Mechanical Engineering
University of California, Berkeley
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