LIBRARY SHELF:

Mechanical Properties

Title: "High frictional anisotropy of periodic and aperiodic directions on a quasicrystal surface"

Authors: J.Y. Park, D.F. Ogletree, M. Salmeron, R.A. Ribeiro, P.C. Canfield, C.J. Jenks, and P.A. Thiel

Contact: P.A. Thiel

Journal: Science (2005) 309, 1354-1356.

Abstract:
None

Title: "Elastic properties of icosahedral i-Cd84Yb16 and hexagonal h-Cd51Yb14"

Authors: J. Schreuer, W. Steurer, T.A. Lograsso, and D. Wu

Contact: T.A. Lograsso

Journal: Philos. Mag. Lett. (2004) 84, 643-653.

Abstract:
The elastic constants, their temperature and pressure derivatives, and coefficients of thermal expansion of the icosahedral quasicrystal i-Cd84Yb16 and of the hexagonal phase h-Cd51Yb14 have been studied by resonant ultrasound spectroscopy, conventional ultrasonic resonance techniques and dilatometry, respectively. The elastic properties of both phases are very similar although they are structurally not related. Contrary to the assumption often found in quasicrystal literature, the similarity of particular physical properties is not necessarily an indication for structural similarity. Further, a first-order phase transition at about 111 K has been observed in h-Cd51Yb14 as indicated by a reversible discontinuity in the thermal expansion.

Title: "Plasticity of icosahedral Zn-Mg-Dy single quasicrystals"

Authors: M. Heggen, M. Feuerbacher, P. Schall, H. Klein, I.R. Fisher, P.C. Canfield, and K. Urban

Contact: P.C. Canfield

Journal: Mater. Sci. Eng., A. (2000) 294-296, 781-785.

Abstract:

We present the results of first deformation experiments on Zn–Mg–Dy icosahedral single quasicrystals. The samples were produced by the flux growth technique. The plastic deformation experiments were performed at temperatures between 490 and 530°C at strain rates of 10-5 and 10-6 s-1. The thermodynamic activation parameters of the deformation process were determined. The stress–strain curves show strong yielding followed by a steady state regime with a constant flow stress level up to strains of about 8%. Microstructural investigations by transmission electron microscopy on deformed samples indicate a deformation mechanism mediated by dislocations. We found a high density of planar defects which were interpreted as slip planes of moving dislocations.

Title: "Comparative study of microstructural and tribological properties of sintered, bulk icosahedral samples"

Authors: P. Brunet, L.M. Zhang, D.J. Sordelet, M. Besser, and J.M. Dubois

Contact: D.J. Sordelet

Journal: Mater. Sci. Eng., A (2000) 294-296, 74-78.

Abstract:

We have investigated a number of quasicrystalline and related samples prepared by sintering under either hot isostatic pressure (HIP) or low uniaxial pressure (LUP). Attention was focused to the influence of the preparation process parameters onto the resulting crystallographic structure and morphology of the phases. Altogether, we found some differences between the two kinds of samples as far as hardness and friction coefficient were concerned. For instance, HIPed specimens containing boron exhibited small rod-shaped precipitates whereas LUPed samples did not. The LUPed specimens revealed better wear resistance and lower friction towards steel and tungsten carbide riders than the HIPed materials. The present study clearly points out that pressure–temperature–composition phase diagrams and preparation processes of quasicrystals, as well as for most other materials, have a significant influence on the final properties which may be eventually used in view of technological applications.

Title: "Plastic deformation of icosahedral Zn-Mg-Dy single quasicrystals"

Authors: M. Heggen, M. Feuerbacher, P. Schall, H. Klein, I.R. Fisher, P.C. Canfield, and K. Urban

Contact: P.C. Canfield

Journal: Philos. Mag. Lett. (2000) 80, 129-136.

Abstract:

Plastic deformation experiments have been performed on Zn-Mg-Dy icosahedral single quasicrystals at temperatures between 490 and 530 °C and at strain rates of 10-5 and 10-6 s-1. The stress-strain curves show strong yielding followed by a steady-state regime with a constant flow stress level up to strains of about 8%. Thermodynamic activation parameters of the deformation process were determined and are discussed in comparison with those found for icosahedral Al-Pd-Mn. Microstructural investigations by transmission electron microscopy on deformed samples were performed and indicate a deformation mechanism mediated by dislocations.

Title: "Mechanical properties of Al-Cu-Fe-based quasicrystalline coatings"

Authors: J.E. Shield, J. Cambell, and D.J. Sordelet

Contact: D.J. Sordelet

Journal: J. Mater. Sci. Lett. (1997) 16(24), 2019-2021.

Abstract:

None

Title: "Deformation characteristics of quasicrystalline Al-Cu-Fe alloys"

Authors: J.E. Shield and M.J. Kramer

Contact: M.J. Kramer

Journal: J. Mater. Res. (1997) 12(8), 2043-2047.

Abstract:

The deformation characteristics of icosahedral Al-Cu-Fe quasicrystals were determined by high temperature creep experiments between 680 and 720 °C and 15 and 41 MPa. The deformation process was determined to be controlled by grain boundary mechanisms. Both the stress and grain size sensitivity exponents were found to be 2, suggesting that grain boundary sliding was the rate-controlling deformation mechanism. Microstructural analysis supported this conclusion, as no intragranular defects were produced during the deformation experiments.

Title: "Deformation-induced planar defects in Al-Cu-Fe quasicrystals"

Authors: J.E. Shield and M.J. Kramer

Contact: M.J. Kramer

Journal: J. Mater. Res. (1997) 12(2), 300-303.

Abstract:

Planar defects were observed in a hot isostatically pressed Al-Cu-Fe alloy. The defects were determined to be perpendicular to the fivefold direction. They were also found to be regions where the quasiperiodicity in the five-fold direction was disrupted, resulting in a periodicity along this direction of 1.06 nm. The defects were stable up to approximately 750 °C. The defects were determined to be formed by the applied shear forces associated with the consolidation process. The displacement vector of the defects was determined to be in a twofold direction perpendicular to the periodic direction.

Title: "Dislocation analysis of deformed Al-Pd-Mn quasicrystals"

Authors: J.E. Shield and M.J. Kramer

Contact: M.J. Kramer

Journal: Scripta Mater. (1996) 35(8), 913-917.

Abstract:

Dislocation analysis was performed on polygrained Al70Pd21.5Mn8.5 icosahedral quasicrystals deformed at high temperature. Using contrast analysis, the Burgers vector was determined to be parallel to a twofold direction, while the line direction was found to be parallel to a different twofold direction. The angle between B and U was found to be 32 ° so that the dislocation has mixed character. The screw component of the dislocation was found to be parallel to a twofold direction, while the edge component was found to be parallel to a pseudo twofold direction. Considering the characteristics of the dislocation, slip could occur on fivefold planes, resulting in 30 slip systems.

Title: "Deformation studies of quasicrystals"

Authors: M.J. Kramer and J.E. Shield

Contact: M.J. Kramer

Proceedings of the Engineering Foundation Conference on Deformations of Cermics, R. C. Bradt, C.A. Brooks and J.L. Routbort edts., Plenum Publishing Corporation, New York, 99-108 (1995).

Abstract:

The microstructures of Al-Cu-Fe and Al-Pd-Mn icosahedral quasicrystals deformed at high temperatures were investigated. Planar defects resembling stacking faults were observed in Al-Cu-Fe. These defects were stable up to at least ~750°C, and were found to have a displacement vector parallel to a twofold direction. In Al-Pd-Mn, the microstructures were indicative of a dislocation-controlled deformation mechanism. The dislocations were determined to have Burgers vectors and line directions parallel to twofold directions, and the dislocations were mixed in character.

Title: "Deformation twinning in a face-centered icosahedral alloy"

Authors: J.E. Shield and M.J. Kramer

Contact: M.J. Kramer

Journal: Philos. Mag. Lett. (1994) 69, 115-121.

Abstract:

We have determined the twinning mode in icosahedral Al65Cu23Fe12 deformed by high temperature creep. The twinning elements K1, K2, h1 and h2 have been determined from electron diffraction experiments. Both of the invariant planes K1 and K2 were determined to be of the fivefold {1/0 0/1 0/0} type, and the two directions h1 and h2 were found to be midway between two twofold directions and of the <1/2 1/1 2/1> or <1/0 1/3 0/1> types. Considering the large amount of shear strain accomodated by this twinning and the large number of possible twin planes, a substantial amount of plastic deformation can be accomodated by deformation twinning in these materials.

Title: "Plastic deformation in an Al-Pd-Mn alloys"

Authors: J.E. Shield, M.J. Kramer, and R.W. McCallum

Contact: M.J. Kramer

Journal: J. Mater. Res. (1994) 9(2), 343-347.

Abstract:

The deformation characteristics of icosahedral Al70Pd21.5Mn8.5 have been investigated by high temperature creep experiments and the resultant microstructures have been examined by transmission electron microscopy (TEM). From 730 to 780°C, microstructural analysis revealed that the deformation is controlled by dislocation glide, with an activation energy of 210 ± 30 kJ/mole and a stress exponent of 1.2 ± 0.2. From 780 to 810°C, microstructures were characteristic of deformation controlled by dislocation glide and climb. The activation energy and stress exponent were determined to be 1700 ± 80 kJ/mol and 2.9 ± 0.3, respectively. Hardness measurements also reflected an increase in dislocation density, as the hardness of the deformed samples was approximately 10% higher than the as-cast sample.

Title: "Plastic deformation in an Al-Cu-Fe icosahedral alloy"

Authors: J.E. Shield, M.J. Kramer, and R.W. McCallum

Contact: M.J. Kramer

Journal: J. Mater. Res. (1993) 8(6), 1199-1201.

Abstract:

Al-Cu-Fe quasicrystalline alloys have been deformed by high temperature creep between 680 and 740°C. Deformations greater than 30% were achieved without cracking. Analysis of the data in the quasi-steady state regime reveals power law behavior with a stress exponent of 2.5. The activation energy for deformation was determined to be 640 ± 20 kJ/mole in the temperature region investigated. Transmission electron microscopy revealed lamellar defects which appear similar to twins.

Title: "A face centered icosahedral approximate phase with local icosahedral symmetry"

Authors: J.E. Shield, M.J. Kramer, R.W. McCallum, and A.I. Goldman

Contact: M.J. Kramer

Physics and Chemistry of Finite Systems: From Clusters to Crystals, Ed. by P. Jena et al., Kluwer Academic Publishers, the Netherlands, 125-129 (1992).

Abstract:

Unavailable


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