Breakage and debonding of short brittle fibres among particulates in a metal matrix

Tvergaard, Viggo

doi:10.1016/j.msea.2003.11.009

Cited by 12 publications

(8 citation statements)

References 17 publications

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“…10 show wavy fluctuation with an amplitude up to about 10 nm, while the original whisker surface before loading is straight. 21 Such out-of-plane deformation was first identified in the present AFM observation for a discontinuously reinforced Ti composite and 12.…”

Section: A Deformation and Failure Of Reinforcementssupporting

confidence: 64%

“…The microstructure of the matrix clearly shows equiaxed ␣ phase and intergranular ␤ phase, as is often seen in a Ti-6Al-4V/TiB composite 4 with similar thermal history. 12,21,22 The evolution of slip band spacing as a function of applied strain measured in three different grains [as marked in Fig. The evolution of the average surface roughness as a function of the applied strain in the composite at four different regions is plotted in Fig.…”

Section: Resultsmentioning

confidence: 99%

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Surface nanodeformation of discontinuously reinforced Ti composite by in situ atomic force microscope observation

et al. 2007

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The surface nanodeformation of a discontinuously reinforced Ti-6Al-4V composite during tensile loading was investigated by in situ atomic force microscope (AFM) observation. The material used was a TiB whisker and TiC particle reinforced Ti-6Al-4V composite. The evolution of surface roughness and slip band spacing was quantified as a function of applied strain. The microstructural damage during tensile loading was also studied. The formation of slip bands within a grain of the Ti-6Al-4V matrix was clearly observed when the applied strain above was 1.3%. The amount of slip bands and surface roughness increase with increasing applied strain. The rupture of TiC particle and multiple cracking of TiB whiskers were also observed at the applied strain above 1.3%. The interaction of slip bands with the reinforcements and mechanisms of deformation and fracture of the composite were elucidated.

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Section: A Deformation and Failure Of Reinforcementssupporting

confidence: 64%

Section: Resultsmentioning

confidence: 99%

Surface nanodeformation of discontinuously reinforced Ti composite by in situ atomic force microscope observation

et al. 2007

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“…see Needleman et al [6]). Axisymmetric cell models containing a single fibre have been used to study failure by debonding at the fibre-matrix interface and subsequent fibre pull-out (Nutt and Needleman [7], Tvergaard [8]) and have also been extended to consider both fibre breakage and debonding (Tvergaard [9,10,11]). The actual three-dimensional fibre distribution is only approximately represented in the axisymmetric analyses, but full 3D numerical cell model analyses (Levy and Papazian [12], Hom [13]) have confirmed a rather good agreement with axisymmetric results.…”

Section: Introductionmentioning

confidence: 99%

Cavitation instabilities between fibres in a metal matrix composite

Tvergaard

2015

Acta Mech

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-Short fibre reinforced metal matrix composites (MMC) are studied here to investigate the possibility that a cavitation instability can develop in the metal matrix. The high stress levels needed for a cavitation instability may occur in metal ceramic systems due to the constraint on plastic flow induced by bonding to the ceramics that only show elastic deformation. In a MMC the stress state in the metal matrix is highly non-uniform, varying between regions where shear stresses are dominant and regions where hydrostatic tension is strong. An Al-SiC whisker composite with a periodic pattern of transversely staggered fibres is here modelled by using an axisymmetric cell model analysis. First the critical stress level is determined for a cavitation instability in an infinite solid made of the Al matrix material. By studying composites with different distributions and aspect ratios of the fibres it is shown that regions between fibre ends may develop hydrostatic tensile stresses high enough to exceed the critical level for a cavitation instability. For cases where a void is located in such regions it is shown that unstable cavity growth develops when the void is initially much smaller than the highly stressed region of material.

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“…Voids arising from cracked particles When voids nucleate by particle cracking rather than by decohesion of the particle-matrix interface, the particles are most likely to crack near the middle where the tensile stresses are highest. This situation is rather similar to fibre breakage in metal matrix composites (MMC), which has been analyzed by Tvergaard (1993Tvergaard ( , 2004 for rigid fibres in a metal matrix. For the initially pennyshaped crack through the particle the mode of deformation is completely dominated by blunting type deformations at the crack-tip.…”

Section: Spheroidal Voids Oblate Spherical or Prolatementioning

confidence: 86%

“…see Nielsen et al, 2010) that the shape evolution from the initial penny-shaped crack is described as that of an oblate void in a homogeneous matrix material. In reality the mode of deformation is very different, more like that at fibre breakage in a metal matrix composite (Tvergaard, 1993(Tvergaard, , 2004, where the fibre or the hard particle deforms very little, while the deformations are highly concentrated in the matrix material around the initial crack-tip. Remeshing makes it possible to analyze this mechanism and to compare with the corresponding oblate void in the homogeneous matrix material.…”

Section: Introductionmentioning

confidence: 99%

Void shape effects and voids starting from cracked inclusion

Tvergaard¹

2011

International Journal of Solids and Structures

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a b s t r a c tNumerical, axisymmetric cell model analyses are used to study the growth of voids in ductile metals, until the mechanism of coalescence with neighbouring voids sets in. A special feature of the present analyses is that extremely small values of the initial void volume fraction are considered, down to 10 À10 , which means that the metal undergoes huge strains before coalescence. This is accounted for in the present analyses by using remeshing techniques. The evolution of the void shape during the large deformations is a natural outcome of the numerical analysis. Also the effect of different initial void shapes is considered, as well as the effect of different spacings between the voids in the axial and transverse directions. While these first analyses are carried out for voids in a homogeneous metal, a second set of cell model studies are carried out for voids that initiate from a crack in a hard second phase particle. As the particle deforms relatively little the void growth is here dominated by strong blunting of the metal at the tip of the initial penny-shaped crack. These analyses are used to estimate how well the void shape evolution would be approximated by assuming that the presence of the particle in the material adjacent to the void can be neglected.

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Breakage and debonding of short brittle fibres among particulates in a metal matrix

Cited by 12 publications

References 17 publications

Surface nanodeformation of discontinuously reinforced Ti composite by in situ atomic force microscope observation

Surface nanodeformation of discontinuously reinforced Ti composite by in situ atomic force microscope observation

Cavitation instabilities between fibres in a metal matrix composite

Void shape effects and voids starting from cracked inclusion

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