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Title: On the Elastic Properties and Mechanical Damping of Ti 3SiC 2, Ti 3GeC 2, TiSi 0.5Al 0.5C 2 and Ti 2AlC, in the 300-1573 K Temperature Range

Abstract

In this paper we report on the temperature dependencies of Young's, E, and shear moduli, {mu}, of polycrystalline Ti3SiC2, Ti2AlC, Ti3GeC2 and Ti3Si0.5Al0.5C2 samples determined by resonant ultrasound spectroscopy in the 300-1573K temperature range. For the isostructural 312 phases, both the longitudinal and shear sound velocities decrease in the following order: Ti3SiC2>Ti3Si0.5Al0.5C2>Ti3AlC2>Ti3GeC2. Like other phases in the same family, these solids are relatively stiff and lightweight. The room temperature E values range between 340 and 277GPa for Ti2AlC to 340GPa for Ti3SiC2; the corresponding {mu} values range between 119 and 144GPa. Poisson's ratio is around 0.19. Both E and {mu} decrease linearly and slowly with increasing temperature for all compositions examined. The loss factor, Q-1, is found to be relatively high and a weak function of grain size and temperature up to a critical temperature, after which it increases significantly. Modest (4% strain) pre-deformation of Ti3SiC2 at elevated temperatures results in roughly an order of magnitude increase in Q-1 as compared to as-sintered samples, which led us to the conclusion that the damping is due to the interaction of dislocation segments with the ultrasound waves. That Q-1 decreases with increasing strain amplitude is consistent with such an interpretation. The lossmore » factors of the deformed Ti3SiC2 sample are orders of magnitude higher than those of typical structural ceramics. The technological implications of having readily machinable solids that have stiffnesses comparable to Si3N4 and damping capabilities comparable to some woods are obvious and are discussed.« less

Authors:
 [1];  [2];  [2];  [2];  [3];  [2];  [1]
  1. ORNL
  2. Drexel University
  3. Thomson TTW R&D Center
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); High Temperature Materials Laboratory
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
OSTI Identifier:
931617
DOE Contract Number:
DE-AC05-00OR22725
Resource Type:
Journal Article
Resource Relation:
Journal Name: Acta Materialia; Journal Volume: 54; Journal Issue: 10
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ELASTICITY; DAMPING; YOUNG MODULUS; TITANIUM CARBIDES; SILICON CARBIDES; ALUMINIUM CARBIDES; GERMANIUM CARBIDES; POISSON RATIO

Citation Formats

Radovic, Miladin, Barsoum, M W, Ganguly, A, Zhen, T, Finkel, P., Kalidindi, S R, and Lara-Curzio, Edgar. On the Elastic Properties and Mechanical Damping of Ti3SiC2, Ti3GeC2, TiSi0.5Al0.5C2 and Ti2AlC, in the 300-1573 K Temperature Range. United States: N. p., 2006. Web. doi:10.1016/j.actamat.2006.02.019.
Radovic, Miladin, Barsoum, M W, Ganguly, A, Zhen, T, Finkel, P., Kalidindi, S R, & Lara-Curzio, Edgar. On the Elastic Properties and Mechanical Damping of Ti3SiC2, Ti3GeC2, TiSi0.5Al0.5C2 and Ti2AlC, in the 300-1573 K Temperature Range. United States. doi:10.1016/j.actamat.2006.02.019.
Radovic, Miladin, Barsoum, M W, Ganguly, A, Zhen, T, Finkel, P., Kalidindi, S R, and Lara-Curzio, Edgar. Sun . "On the Elastic Properties and Mechanical Damping of Ti3SiC2, Ti3GeC2, TiSi0.5Al0.5C2 and Ti2AlC, in the 300-1573 K Temperature Range". United States. doi:10.1016/j.actamat.2006.02.019.
@article{osti_931617,
title = {On the Elastic Properties and Mechanical Damping of Ti3SiC2, Ti3GeC2, TiSi0.5Al0.5C2 and Ti2AlC, in the 300-1573 K Temperature Range},
author = {Radovic, Miladin and Barsoum, M W and Ganguly, A and Zhen, T and Finkel, P. and Kalidindi, S R and Lara-Curzio, Edgar},
abstractNote = {In this paper we report on the temperature dependencies of Young's, E, and shear moduli, {mu}, of polycrystalline Ti3SiC2, Ti2AlC, Ti3GeC2 and Ti3Si0.5Al0.5C2 samples determined by resonant ultrasound spectroscopy in the 300-1573K temperature range. For the isostructural 312 phases, both the longitudinal and shear sound velocities decrease in the following order: Ti3SiC2>Ti3Si0.5Al0.5C2>Ti3AlC2>Ti3GeC2. Like other phases in the same family, these solids are relatively stiff and lightweight. The room temperature E values range between 340 and 277GPa for Ti2AlC to 340GPa for Ti3SiC2; the corresponding {mu} values range between 119 and 144GPa. Poisson's ratio is around 0.19. Both E and {mu} decrease linearly and slowly with increasing temperature for all compositions examined. The loss factor, Q-1, is found to be relatively high and a weak function of grain size and temperature up to a critical temperature, after which it increases significantly. Modest (4% strain) pre-deformation of Ti3SiC2 at elevated temperatures results in roughly an order of magnitude increase in Q-1 as compared to as-sintered samples, which led us to the conclusion that the damping is due to the interaction of dislocation segments with the ultrasound waves. That Q-1 decreases with increasing strain amplitude is consistent with such an interpretation. The loss factors of the deformed Ti3SiC2 sample are orders of magnitude higher than those of typical structural ceramics. The technological implications of having readily machinable solids that have stiffnesses comparable to Si3N4 and damping capabilities comparable to some woods are obvious and are discussed.},
doi = {10.1016/j.actamat.2006.02.019},
journal = {Acta Materialia},
number = 10,
volume = 54,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2006},
month = {Sun Jan 01 00:00:00 EST 2006}
}
  • Herein we report on the formation of defects in response to neutron irradiation of polycrystalline Ti 3SiC 2 and Ti 3AlC 2 samples exposed to doses of 0.14±0.01, 1.6±0.1, and 3.4±0.1 displacements per atom (dpa) at irradiation temperatures of 121±12, 735±6 and 1085±68 °C. After irradiation to 0.14 dpa at 121 °C and 735 °C, black spots are observed in both Ti 3SiC 2 and Ti 3AlC 2. After irradiation to 1.6 and 3.4 dpa at 735 °C, basal dislocation loops, with a Burgers vector of b = ½ [0001] are observed in Ti 3SiC 2, with loop diameters ofmore » 21±6 and 30±8 nm for 1.6 dpa and 3.4 dpa, respectively. In Ti3AlC2, larger dislocation loops, 75±34 nm in diameter are observed after 3.4 dpa at 735 °C, in addition to stacking faults. Impurity particles of TiC, as well as stacking fault TiC platelets in the MAX phases, are seen to form extensive dislocation loops under all conditions. Voids are observed at grain boundaries and within stacking faults after 3.4 dpa irradiation, with extensive void formation in the TiC regions at 1085 °C. Remarkably, denuded zones on the order of 1 µm are observed in Ti 3SiC 2 after irradiation to 3.4 dpa at 735 °C. Small grains, 3-5 µm in diameter, are damage free after irradiation at 1085 °C at this dose. The presence of the A-layer in the MAX phases is seen to provide enhanced irradiation tolerance. Based on these results, and up to 3.41 dpa, Ti 3SiC 2 remains a promising candidate for high temperature nuclear applications.« less
  • The structural inheritance and difference between Ti 2AlC, Ti 3AlC 2 and Ti 5Al 2C 3 under pressure from first principles are studied. The results indicate that the lattice parameter a are almost the same within Ti 2AlC, Ti 3AlC 2 and Ti 5Al 2C 3, and the value of c in Ti 5Al 2C 3 is the sum of Ti 2AlC and Ti 3AlC 2 which is revealed by the covalently bonded chain in the electron density difference: Al–Ti–C–Ti–Al for Ti 2AlC, Al–Ti 2–C–Ti 1–C–Ti 2–Al for Ti 3AlC 2 and Al–Ti 3–C 2–Ti 3–Al–Ti 2–C 1–Ti 1–C 1–Timore » 2–Al for Ti 5Al 2C 3. The calculated axial compressibilities, volumetric shrinkage, elastic constant c 11, c 33/c 11 ratio, bulk modulus, shear modulus, and Young’s modulus of Ti 5Al 2C 3 are within the range of the end members (Ti 2AlC and Ti 3AlC 2) in a wide pressure range of 0–100 GPa. Only Ti 2AlC is isotropic crystal at about 50 GPa within the Ti–Al–C compounds. All of the Ti 3 d density of states curves of the three compounds move from lower energy to higher energy level with pressure increasing. The similarities of respective bond length, bond overlap population (Ti–C, Ti–Al and Ti–Ti), atom Mulliken charges under pressure as well as the electron density difference for the three compounds are discovered. Among the Ti–Al–C ternary compounds, Ti–Ti bond behaves least compressibility, whereas the Ti–Al bond is softer than that of Ti–C bonds, which can also been confirmed by the density of states and electron density difference. Bond overlap populations of Ti–Ti, Ti–C and Ti–Al indicate that the ionicity interaction becomes more and more stronger in the three structures as the pressure increasing. Lastly, Mulliken charges of Ti 1, Ti 2, Ti 3, C and Al are 0.65, 0.42, 0.39, –0.73, –0.04 at 0 GPa, respectively, which are consistent with the Pauling scale.« less