Journal ArticleDOI
In Situ Toughened Silicon Carbide with Al‐B‐C Additions
TLDR
In this paper, the microstructures, secondary phases, and grain boundaries were characterized using a range of analytical techniques including TEM, SEM, AES, and XRD, and the fracture toughness was derived either from bend tests of beam-shaped samples with a controlled surface flaw or from standard disk-shaped compact-tension specimens precracked in cyclic fatigue.Abstract:
“In situ toughened” silicon carbides, containing Al, B, and C additives, were prepared by hot pressing. Densification, phase transformations, and microstructural development were described. The microstructures, secondary phases, and grain boundaries were characterized using a range of analytical techniques including TEM, SEM, AES, and XRD. The modulus of rupture was determined from fourpoint bend tests, while the fracture toughness was derived either from bend tests of beam-shaped samples with a controlled surface flaw, or from standard disk-shaped compact-tension specimens precracked in cyclic fatigue. The R-curve behavior of an in situ toughened SiC was also examined. A steady-state toughness over 9 MPa·m1/2 was recorded for the silicon carbide prepared with minimal additives under optimum processing conditions. This increase in fracture toughness, more than a factor of three compared to that of a commercial SiC, was achieved while maintaining a bend strength of 650 MPa. The mechanical properties were found to be related to a microstructure in which platelike grain development had been promoted and where crack bridging by intact grains was a principal source of toughening.read more
Citations
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Journal ArticleDOI
Tough, bio-inspired hybrid materials.
Etienne Munch,Maximimilan E. Launey,Daan Hein Alsem,Daan Hein Alsem,Eduardo Saiz,Antoni P. Tomsia,Robert O. Ritchie,Robert O. Ritchie +7 more
TL;DR: In this article, the authors emulate Nature's toughening mechanisms through the combination of two ordinary compounds, aluminum oxide and polymethylmethacrylate, into ice-templated structures whose toughness can be over 300 times (in energy terms) that of their constituents.
Journal Article
Tough, bio-inspired hybrid materials
TL;DR: This work emulates nature's toughening mechanisms by combining two ordinary compounds, aluminum oxide and polymethyl methacrylate, into ice-templated structures whose toughness can be more than 300 times that of their constituents.
Journal ArticleDOI
On the fracture toughness of advanced materials
TL;DR: In this article, the authors show that the ability of a microstructure to develop toughening mechanisms acting either ahead or behind the crack tip can result in resistance-curve behavior where the fracture resistance actually increases with crack extension; the implication here is that toughness is often developed primarily during crack growth and not for crack initiation.
Journal ArticleDOI
Grain Boundary Complexions
TL;DR: Grain boundary complexion transitions are the root cause of a wide variety of materials phenomena such as abnormal grain growth, grain boundary embrittlement and activated sintering as discussed by the authors, which have defied mechanistic explanation for years.
Journal ArticleDOI
Ceramics for Prosthetic Hip and Knee Joint Replacement
TL;DR: The structure, properties, applications, and limitations of the ceramics that have been used in orthopedic bearings are reviewed, and the new ceramic composite materials and surface treatments that will be available for joint replacement surgery in the near future are described.
References
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Journal ArticleDOI
Crack deflection processes—I. Theory
TL;DR: In this article, a fracture mechanics approach has been used to predict fracture toughness increases due to crack deflection around second phase particles, based on a determination of the initial tilt and the maximum twist of the crack front between particles.
Journal ArticleDOI
A Critical Evaluation of Indentation Techniques for Measuring Fracture Toughness: II, Strength Method
TL;DR: In this paper, the sharp-indentation technique of strength-test precracking for toughness evaluation is examined and the residual-stress term discussed in Part I of this study is now introduced explicitly into the strength formulation.
Book ChapterDOI
Stress Analysis of Cracks
Paul C. Paris,G.C. Sih +1 more
TL;DR: Elastic stress analyses of cracked bodies represented by stress intensity factor method - fracture mechanics as discussed by the authors, and fracture mechanics are used for fracture mechanics. But they are not suitable for fracture analysis.
Journal ArticleDOI
Microstructural design of toughened ceramics
TL;DR: In this article, the authors discute des mecanismes de renforcement des ceramiques par pontage des fissures a l'aide de trichites and d'autres types de renforcants discontinus.
Journal ArticleDOI
In situ-toughened silicon carbide
TL;DR: In this article, an atmospheric pressure sintering strategy for obtaining dense SiC-based materials with microstructures consisting of uniformly distributed elongate-shaped [alpha]-SiC grains and relatively high amounts of second-phase yttrium aluminum garnet (YAG) was presented.
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