The transient plastic phase processing of ceramic-ceramic composites

Barsoum, Michel W.; Zavaliangos, Antonios; Kalidindi, Surya R.; El‐Raghy, T.; Brodkin, Dmitri

doi:10.1007/bf03221311

Cited by 13 publications

(13 citation statements)

References 7 publications

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“…[21,33] The formation of platelet morphology (Figure 9(d)) of the ZrB 2 /ZrC x is similar to that seen in melt infiltrated samples containing excess Zr metal [6][7][8][9][10] and those samples produced in two-stage processing. [17] In the present study, it is also noticed that the unreacted B 4 C was accompanied by the presence of ZrB 2 platelets from which one may conclude that free Zr also exists. As the reaction progresses, the metal is eliminated with the formation of ZrB 2 -ZrC x~0.67 phases and results in an equiaxed microstructure (Figures 10(a) and (b)).…”

Section: B Effect Of Nonstoichiometry On Reaction and Densification mentioning

confidence: 75%

“…[16] The two-stage transient plastic phase processing of three different molar ratios of Zr to B 4 C (3:1, 3.5:1, and 4:1) at a final temperature of 1600°C for 4 hours yielded ZrB 2 -ZrC composites with full density. [17] It has been recently shown that high energy milling of elemental Zr and B can be used to produce ZrB 2 at temperatures as low as 600°C, and dense ZrB 2 -SiC composites can be obtained at 1700°C. [18] Because boron compounds are cheaper and easier to handle, the present study is undertaken to systematically establish the possibility of lowering the process temperature by reactive densification of ZrB 2 -ZrC composites starting with Zr and B 4 C powders.…”

Section: Introductionmentioning

confidence: 99%

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Low-Temperature Processing of ZrB2-ZrC Composites by Reactive Hot Pressing

Rangaraj

Suresha

Divakar

et al. 2008

Metall Mater Trans A

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LINGAPPA RANGARAJ, SIRIYARA J. SURESHA, CANCHI DIVAKAR, and VIKRAM JAYARAM Dense ZrB 2 -ZrC and ZrB 2 -ZrC x~0.67 composites have been produced by reactive hot pressing (RHP) of stoichiometric and nonstoichiometric mixtures of Zr and B 4 C powders at 40 MPa and temperatures up to 1600°C for 30 minutes. The role of Ni addition on reaction kinetics and densification of the composites has been studied. Composites of~97 pct relative density (RD) have been produced with the stoichiometric mixture at 1600°C, while the composite with 99 pct RD has been obtained with excess Zr at 1200°C, suggesting the formation of carbon deficient ZrC x that significantly aids densification by plastic flow and vacancy diffusion mechanism. Stoichiometric and nonstoichiometric composites have a hardness of~20 GPa. The grain sizes of ZrB 2 and ZrC x~0.67 are~0.6 and 0.4 lm, respectively, which are finer than those reported in the literature.

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Section: B Effect Of Nonstoichiometry On Reaction and Densification mentioning

confidence: 75%

Section: Introductionmentioning

confidence: 99%

Low-Temperature Processing of ZrB2-ZrC Composites by Reactive Hot Pressing

Rangaraj

Suresha

Divakar

et al. 2008

Metall Mater Trans A

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“…So it was concluded that most of the densification by the metal was undone by this volume shrinkage, and that plasticity of transient TiC x was essential to produce a fully densified TiB 2 -TiC x . Starting with a TiC 0.5 -TiB 2 powder mixture also showed that the same densification can be achieved as in a 4Ti:B 4 C powder mixture (which would yield the same final product) after HP at same temperature and pressure, 12 thus conclusively proving the role of plastic flow of transient carbide phases in the densification.…”

Section: Introductionmentioning

confidence: 75%

“…[10][11][12] Even though the soft metal was assumed to contribute to densification in that work, the primary emphasis was given to plasticity of the transient carbide phases, and for good reason. Carbide formation is intrinsically intertwined with a large amount of volume shrinkage that largely negates the densification by the soft metal.…”

Section: Introductionmentioning

confidence: 99%

Effect of Zirconium on the Densification of Reactively Hot‐Pressed Zirconium Carbide

2014

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Densification mechanisms involved during reactive hot pressing (RHP) of zirconium carbide (ZrC) have been studied. RHP has been carried out using zirconium (Zr) and graphite (C) powders in the molar ratios 1:0.5, 1:0.67, 1:0.8, and 1:1 at 40 MPa, 800°C-1200°C for different durations. The volume fractions of phases formed, including porosity, are determined from the measured density and from Rietveld analysis. Increased densification with an increasing nonstoichiometry in carbon has been observed. Microstructural and X-ray diffraction observations coupled with the predictions of a model based on the constitutive laws governing plastic flow of zirconium suggest that the better densification of nonstoichiometric compositions arise from the higher amount of starting Zr and also the longer duration of its availability for plastic flow during RHP. Volume shrinkage due to reaction between Zr and C and the gradual elimination of the soft metal phase limit the final density achievable. Based on these observations, a twostep RHP carried out at 800°C and 1200°C leads to a better densification than a single RHP at 1200°C.

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“…In 1996, we made use of a reactive hot pressing (HPing), process termed transient plastic phase processing (Barsoum and Houng, 1993) to fabricate, in one step, starting with TiH 2 , SiC, and graphite, fully dense predominantly single-phase samples of Ti 3 SiC 2 . Significantly, the processing temperature (1600 • C) was, at that time, considered to be above the decomposition temperature of this phase.…”

Section: History Since 1995mentioning

confidence: 99%

Introduction

2013

MAX Phases

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The M n+1 AX n , or MAX, phases are layered, hexagonal, early transition-metal carbides and nitrides, where n = 1, 2, or 3 ''M'' is an early transition metal, ''A'' is an A-group (mostly groups 13 and 14) element, and ''X'' is C and/or N. In every case, near-close-packed M layers are interleaved with layers of pure group-A element with the X atoms filling the octahedral sites between the former (Figure 1.1a-c). The M 6 X octahedra are edge-sharing and are identical to those found in the rock salt structure. The A-group elements are located at the center of trigonal prisms that are larger than the octahedral sites and thus better able to accommodate the larger A atoms. The main difference between the structures with various n values ( Figure 1.1a-c) is in the number of M layers separating the A layers: in the M 2 AX, or 211, phases, there are two; in the M 3 AX 2 , or 312, phases there are three; and in the M 4 AX 3 , or 413, phases, there are four. As discussed in more detail in later chapters, this layering is crucial and fundamental to understanding MAX-phase properties in general, and their mechanical properties in particular. Currently, the MAX phases number over 60 (Figure 1.2) with new ones, especially 413s and solid solutions, still being discovered.Most of the MAX phases are 211 phases, some are 312s, and the rest are 413s. The M group elements include Ti, V, Cr, Zr, Nb, Mo, Hf, and Ta. The A elements include Al, Si, P, S, Ga, Ge, As, Cd, In, Sn, Tl, and Pb. The X elements are either C and/or N.Thermally, elastically, and electrically, the MAX phases share many of the advantageous attributes of their respective binary metal carbides or nitrides: they are elastically stiff, and electrically and thermally conductive. Mechanically, however, they cannot be more different: they are readily machinable -remarkably a simple hack-saw will do (Figure 1.3) -relatively soft, resistant to thermal shock, and unusually damage-tolerant. They are the only polycrystalline solids that deform by a combination of kink and shear band formation, together with the delaminations of individual grains. Dislocations multiply and are mobile at room temperature, glide exclusively on the basal planes, and are overwhelmingly arranged either MAX Phases: Properties of Machinable Ternary Carbides and Nitrides, First Edition. Michel W. Barsoum.

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The transient plastic phase processing of ceramic-ceramic composites

Cited by 13 publications

References 7 publications

Low-Temperature Processing of ZrB2-ZrC Composites by Reactive Hot Pressing

Low-Temperature Processing of ZrB2-ZrC Composites by Reactive Hot Pressing

Effect of Zirconium on the Densification of Reactively Hot‐Pressed Zirconium Carbide

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