Electron microscopy of reaction layers between SiC and Ti–6Al–4V after laser embedding

Kloosterman, A.B; Kooi, Bart J.; Hosson, J.T.M. de

doi:10.1016/s1359-6454(98)00265-1

Cited by 89 publications

(50 citation statements)

References 19 publications

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“…Each measurement is represented by a pixel in the obtained orientation micrographs, to which a color or gray scale value is assigned on the basis of the local details of lattice orientation or the quality of the corresponding EBSP. Misorientation distribution, texture and grain boundary structure can then be analyzed on the basis of orientation maps [13]. In the case of OIM scans over a cross section of the laser tracks, the sample reference frame was defined in such a way that the reference direction (RD) is taken vertically downwards from the top.…”

Section: Methodsmentioning

confidence: 99%

Five-fold branched Si particles in laser clad AlSi functionally graded materials

Pei

Hosson

2001

Acta Materialia

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Abstract-Many five-fold branched Si particles (Si p ) were observed in Al-40 wt% Si functionally graded materials produced by a single-step laser cladding process on cast Al-alloy substrate. In this paper the fivefold twinning and growth features of Si p are scrutinized with orientation imaging microscopy and electron microscopic examination. It is a more in depth study of formation of the Si particles in functionally graded materials as published in our previous paper [Pei, Y. T. and De Hosson, J. Th. M., Acta mater., 2000, 48, 2617]. These Si particles have grown from twinned decahedron nuclei consisting of five tetrahedrons that share a common 110 axis. The twin plane re-entrant edge (TPRE) mechanism explains both the branch growth in the radial direction and the elongation of Si p along their common 110 axis. Subsequent twinning within the twinned tetrahedrons provides additional re-entrant grooves on their top faces, which are important for the rapid elongation and consequently for the continuous growth of the branched particle. The 7.5°m ismatch that arises by putting together five tetrahedrons around a common 110 axis is accommodated by small-angle grain boundaries (SAGBs). The SAGBs may disturb the progress of growth steps, which causes the particles to branch. The most remarkable facts of the study are that the five-fold branched silicon particles are much bigger (25ෂ40 µm) than the nanometer sizes previously reported in the literature and the 7.5°m ismatch is accommodated mainly by multiple SAGBs. The examples of a single SAGB reported before are just a special case of the SAGB mechanism.

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Section: Methodsmentioning

confidence: 99%

Five-fold branched Si particles in laser clad AlSi functionally graded materials

Pei

Hosson

2001

Acta Materialia

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“…Details about the laser process with controlled injection of particles in the melt pool are given in Refs [2,3]. The laser beam is transported by means of ®bre optics, resulting in a homogeneous intensity distribution.…”

Section: Methodsmentioning

confidence: 99%

“…The wear rate (weight loss) for abrasive wear diminished by a factor of seven for the SiC embedded Ti±6Al± 4V compared to the untreated material (as tested under identical conditions). Also a pin on ring test for sliding wear under conditions of boundary lubrication indicated a substantial improvement because of the SiC particles embedded [2,3]. Apparently the SiC particles are bonded well to the Ti matrix contributing to the improved wear resistance.…”

Section: Introductionmentioning

confidence: 99%

“…For laser embedding SiC particles in Ti, the particles can be preplaced on the Ti surface [9,10] or they can be injected into the laser melt pool [11,12], which gives large dierences in the respective heat absorption of the particles and the matrix and consequently result in very dierent microstructures. A particle injection process is used in the present work [2,3] and the work is therefore most similar to the one reported in Refs [11,12]. However, the present characterization of the microstructure is intended to be more comprehensive.…”

Section: Introductionmentioning

confidence: 99%

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Reaction layers around SiC particles in Ti: an electron microscopy study

et al. 1999

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AbstractÐA detailed description is given of the microstructure of the top layer of Ti±6Al±4V with SiC particles embedded with a high-power Nd:Yag laser system. Scanning electron microscopy (SEM), as well as conventional, analytical and high-resolution transmission electron microscopy (TEM) were used. An existing controversy about the presence or absence of Ti 3 SiC 2 in the reactive SiC/Ti systems is clari®ed and the ®rst observations of Ti 5 Si 3 precipitation on stacking faults in Si supersaturated TiC are reported. The Si released during the reaction SiC+Ti4TiC+Si results in the formation of Ti 5 Si 3 . If in the reaction layer regions in between the TiC grains become enclosed, the rejected Si content increases locally and Ti 3 SiC 2 plates with dominant (0001) facets nucleate. In the TiC grains particularly of the cellular reaction layer, a high density of widely extending stacking faults of the order of 100 nm is observed and on these faults in many instances small Ti 5 Si 3 precipitates are present. #

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“…Actually our explanation is quite simple. We suggest that the observed TiC is formed directly in an exothermic reaction between the Ti matrix and the SiC particles that were injected during a process employing a high-power laser [1][2]. TiC is the phase with the highest melting point and is the first phase to form in the melt pool near or at the surface of the dissolving SiC particles.…”

Section: Introductionmentioning

confidence: 94%

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Kooi

Hosson

2000

Scripta Materialia

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Electron microscopy of reaction layers between SiC and Ti–6Al–4V after laser embedding

Cited by 89 publications

References 19 publications

Five-fold branched Si particles in laser clad AlSi functionally graded materials

Five-fold branched Si particles in laser clad AlSi functionally graded materials

Reaction layers around SiC particles in Ti: an electron microscopy study

Reply to comment on “reaction layers around SiC particles in Ti: an electron microscopy study”

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