In-situ neutron diffraction of titanium silicide, Ti5Si3, during self-propagating high-temperature synthesis (SHS)

Riley, Daniel P.; Oliver, C.P; Kisi, Erich H.

doi:10.1016/j.intermet.2005.04.004

Cited by 65 publications

(42 citation statements)

References 20 publications

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“…Ti 5 Si 3 formation was reported to be exothermal with a formation energy of 579 kJ/mol. 16) After this exothermal reaction, the materials will experience a contraction that resulted in the decrease in the slope in stage K 4 , which finally resumed the diffusion controlled shrinkage displacement.…”

Section: Resultsmentioning

confidence: 99%

Liquid Reaction during Synthesis of Ti3SiC2 through Pulse Discharge Sintering Ti/Si/TiC Mixed Powders

et al. 2006

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To understand the synthesis mechanism of Ti 3 SiC 2 through pulse discharge sintering Ti/Si/TiC mixed powders, the shrinkage displacement curves were studied during sintering process. Liquid reaction above Ti-Ti 5 Si 3 eutectic temperature was revealed. The Ti-Si liquid reaction was found not only to have assisted the Ti 3 SiC 2 phase formation but also accelerated its densification. Ti 8 C 5 was found to be the intermediate phase during this liquid reaction stage.

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Section: Resultsmentioning

confidence: 99%

Liquid Reaction during Synthesis of Ti3SiC2 through Pulse Discharge Sintering Ti/Si/TiC Mixed Powders

et al. 2006

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“…It has been extensively investigated as a potential reinforcement for MMCs because of the high melting point, low density, high hardness as well as good strength at elevated temperatures. 8,9) Recently, a few works have been carried out to synthesize of Ti 5 Si 3 through combustion synthesis reaction between Ti and Si powders with an ignition temperature of 1 600 K. 8,10) However, the high ignition temperature on the formation of TiSi compounds restricts its application for modern industry as a TiSi MMC. Therefore, it is necessary to find a simple way to fabricate TiSi MMCs at a relative low temperature.…”

Section: )mentioning

confidence: 99%

Fabrication of in Situ TiSi (Ti5Si3, TiSi)/TiC Local Reinforced Steel Matrix Composite via Combustion Synthesis

Yú

Sun

et al. 2009

ISIJ Int.

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An in situ TiSi (Ti 5 Si 3 , TiSi)/TiC local reinforced steel matrix composite was successfully fabricated via combustion synthesis of Cu-Ti-Si system. XRD results show that the reinforced region of the composites is composed of Fe, Cu, TiSi and Ti 5 Si 3 as well as TiC phases. SEM observation shows that the morphologies of the Ti 5 Si 3 particles are coarse acicular/irregular particles and short fibrous/coarse elliptic shape in transition and reinforced region, respectively. TiC particles lie in transition region near the interface and their morphologies are polygon/quadrangle, with sizes ofϳ74 mm DTA analyses show that, without addition of Cu, slight TiSi (TiSi 2 and Ti 5 Si 3 ) compounds form via solid diffusion process. After addition of Cu, Cu and Ti reaction occurs firstly, forming a serious of Cu-Ti compounds, at the same time, the reaction heat ignites the subsequent reaction of CuTi and Si and according forms TiSi (Ti 5 Si 3 ) compounds.KEY WORDS: steel matrix composites; in situ reinforced locally; microstructures; combustion synthesis. 1401© 2009 ISIJ the TiSi MMCs can be fabricated at a relative low temperature.In the previous work of our group, a local in situ AlTiSi reinforced aluminium composite was successfully synthesized by SHS-cast process with reaction system of Al-Ti-Si.11) The purpose of this study is to develop a simplified route to produce a high quality TiSi particle reinforced steel MMCs. Thermodynamic ConsiderationDuring the exothermic reactions in powder mixtures, Cu, Ti and Si may interact to form possible products due to the existence of the following chemical reactions. The Gibbs free energy, DG Q of reactions (1)- (7) has been calculated using the thermodynamic data from literature 12,13) and their results are shown in Fig. 2. Note that the overall 1 mol of the reactants was used for the calculation of changes in the Gibbs free energy, DG Q and the adiabatic temperature, T ad in order to compare the feasibility and tendency of these reactions. It can be seen that the DG Q of these reactions are all negative, which indicates that the seven reactions can take place. The DG Q of reactions (5)-(7) are less than those of reactions of (1)-(4), which indicates that reactions (5)-(7) are most likely to occur. Accordingly, it can be concluded that the displacement reaction (8) In order to confirm whether or not the combustion reactions can self-sustain, the critical value of copper content can be estimated by calculation of adiabatic temperature T ad . It is well known, in a combustion synthesis reaction process, the possible maximum temperature of an exothermic reaction can attain under adiabatic conditions. This maximum temperature is adiabatic temperature T ad , which can be calculated from the heat capacities and enthalpies of formation and transformation. 14) Usually, T ad can be used to ascertain whether or not a synthesis for a given material can be accomplished by a combustion synthesis method. It has been empirically suggested that combustion will not become self-sustaining unles...

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“…[18][19][20][21] Its outstanding features portray it to be a good potential reinforcing candidate in iron and steel matrixes.…”

Section: Introductionmentioning

confidence: 99%

“…XRD results reveal that the local reinforcing region consists of a-Fe, Ti 5 Si 3 and Fe 2 Ti phases, indicating that the SHS reaction did occur in Fe-Ti-Si system. According to the Ti-Si euqilibrim phase diagram, 19) Ti 5 Si 3 is the only phase of the five Ti x Si y intermetallic phases to exhibit a degree of non-stoichiometry (Si solubility of 3.3 wt%) over a temperature range of 1 443-1 603 K. The XRD results show that some Ti atoms react with Fe to form Fe 2 Ti; consequently, it is believed that the Ti 5 Si 3 formed in the present study is a non-stoichiometric compound, since the Ti and Si atoms are at a molar ratio of 5 : 3 in the starting materials. It should be noted that, although, it cannot rule out the possibility of some Ti and Si atoms dissolving in Fe melt to form a-Fe solid solution.…”

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confidence: 99%

In Situ Synthesis of Ti5Si3 Intermetallic Particulate Locally Reinforced Medium Carbon Steel-matrix Composite via the SHS Reaction of Fe–Ti–Si System during Casting

Wang

Guan

et al. 2007

ISIJ Int.

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The in situ Ti 5 Si 3 intermetallic particulate locally reinforced steel matrix composites are successfully fabricated by the self-propagating high-temperature synthesis (SHS) reaction of Fe-Ti-Si system during casting, and the microstructures of the composites reveal a relatively uniform distribution of mango-like Ti 5 Si 3 particulates in the local reinforcing regions. XRD results reveal that in addition to a-Fe and Ti 5 Si 3 phases, the transient Fe 2 Ti is also present in the local reinforcing region of the composites. Furthermore, some Ti 3 SiC 2 particulates are formed and distribute in the limited region nearby the interface between the local reinforcing region and steel matrix. With Fe content increasing from 10 to 30 wt% in the preforms, the Ti 5 Si 3 particulate size is decreased obviously in the local reinforcing region; furthermore, the presence of significant porosity can be detected in the composite synthesized by the 10 wt% Fe-Ti-Si system; on the contrary, only a minimal porosity can be found in that synthesized by 30 wt% Fe in Fe-Ti-Si system. The macro-and micro-hardness as well as the wear resistance of the local reinforcing region are obviously higher than those of the unreinforced medium steel. Improvements in hardness and wear resistance of the composite are mainly attributed to the presence of high volume fraction of hard intermetallic Ti 5 Si 3 particulates.KEY WORDS: in situ; intermetallic; locally reinforced; steel matrix composite; SHS. Experimental ProcedureIn this study, the starting materials were made of commercial powders of 10, 20, 30, 40 and 50 wt% Fe (99.0% purity, ϳ10 mm), Ti (99.5 % purity, ϳ38 mm), and Si (99.5 % purity, ϳ15 mm), respectively. Titanium and silicon powders were used in a ratio corresponding to that of stoichiometric Ti 5 Si 3 . Powder blends with different starting compositions were dry-mixed sufficiently by a ball milling for 6 h in a cylindrical stainless steel jar containing GCr15 bearing steel balls with a ball to powder weight ratio of about 5 : 1 by mechanical rotation at 40 rpm, and then were cold-isostatically pressed into cylindrical preforms (about 20 mm diameter and 10 mm length) by using a stainless steel die with two plungers. The green preforms were pressed uniaxially at pressure ranging from 88-92 MPa to obtain relative densities of 63Ϯ2% theoretical density. Then the preforms were placed and fixed on the side of the sand mold, respectively, as schematically illustrated in Fig. 2 in Ref. 11). Subsequently, the medium carbon steel melt, which composition is measured by an ARL4460 Metals Analyzer and shown in Table 1, prepared by non-oxidation process in a 5 kg medium-frequency induction furnace with a temperature of about 1 600°C was poured into the mold to ignite the SHS reaction of the preforms. After solidification and cooling, composite castings were removed and sectioned in the side position.Vickers microhardness values of the matrix and local reinforcing region in the samples were tested under a load of 50 g with an indentarion time of 10...

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In-situ neutron diffraction of titanium silicide, Ti5Si3, during self-propagating high-temperature synthesis (SHS)

Cited by 65 publications

References 20 publications

Liquid Reaction during Synthesis of Ti<SUB>3</SUB>SiC<SUB>2</SUB> through Pulse Discharge Sintering Ti/Si/TiC Mixed Powders

Liquid Reaction during Synthesis of Ti<SUB>3</SUB>SiC<SUB>2</SUB> through Pulse Discharge Sintering Ti/Si/TiC Mixed Powders

<b>Fabrication of <i>in Situ</i></b> TiSi (Ti<sub>5</sub>Si<sub>3</sub>, TiSi)/TiC Local Reinforced Steel Matrix Composite <i>via</i> Combustion Synthesis

In Situ Synthesis of Ti5Si3 Intermetallic Particulate Locally Reinforced Medium Carbon Steel-matrix Composite via the SHS Reaction of Fe–Ti–Si System during Casting

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