On grain refinement of a γ-TiAl alloy using cryo-milling followed by spark plasma sintering

Shanmugasundaram, T.; Guyon, Julien; Monchoux, Jean‐Philippe; Hazotte, Alain; Bouzy, Emmanuel

doi:10.1016/j.intermet.2015.07.007

Cited by 26 publications

(12 citation statements)

References 46 publications

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“…Densification of TiAl under pressure was first investigated using the hot isostatic pressing (HIP) technique by Choi et al [26], where power law creep was identified to be the densification mechanism from an analysis of macroscopic kinetics. Densification by SPS has been studied using elemental [27,28] and pre-alloyed [22,[29][30][31][32][33][34][35][36] powders. Results reported in these studies showed that densification occurs in a few minutes [22,29,31,36], and that the kinetics depends on the initial microstructure of the powder particles [32,35].…”

Section: Introductionmentioning

confidence: 99%

Densification of Ni and TiAl by SPS: Kinetics and Microscopic Mechanisms

Trzaska

Cours

Monchoux

2018

Metall Mater Trans A

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Densification by spark plasma sintering (SPS) of ductile (Ni) and brittle (TiAl) metallic materials have been studied to elucidate the mechanism of densification in the two cases. Isothermal densification experiments were carried out to determine the activation parameters in Ni. Transmission electron microscopy (TEM) observations of thin foils extracted by focused ion beam (FIB) in the contact regions between particles of TiAl and Ni powders are presented. Macroscopically, the most striking feature observed here is that the densification of Ni takes place in the wide temperature range of 0.2-1.0 Tm, whereas that of TiAl varies in 0.7-0.9 Tm, which is significantly narrower (Tm being the melting temperature of Ni and the peritectic temperature of TiAl). In Ni, the low activation energy (164 ± 30 kJ/mol), the high dislocation density in the inter-particle contact region, and the formation of recovery cells involving dislocation climb, indicate that the rate-controlling mechanism is probably self-diffusion in dislocations. In TiAl, high dislocation densities leading to reorganization into sub-boundaries point to dislocation climb mechanisms, which are kinetically controlled by volume diffusion. The difference in densification kinetics between Ni and TiAl is then accounted for in terms of the difference in their respective rate-controlling mechanisms operative during densification.

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Section: Introductionmentioning

confidence: 99%

Densification of Ni and TiAl by SPS: Kinetics and Microscopic Mechanisms

Trzaska

Cours

Monchoux

2018

Metall Mater Trans A

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“…Under pressure, powder particles were closely rearranged from the disordered state of initial charging and a large number of defects were produced at the contact point. Relevant studies have demonstrated that a high defect density can accelerate the initial sintering process . Trzaslca Zofia used focused ion beam technology (FIB) to extract TEM thin foil at sintering neck and particle center, respectively.…”

Section: Resultsmentioning

confidence: 99%

Densification Mechanism and Microstructure Evolution of Ti‐48Al‐2Cr‐8Nb Alloy by Spark Plasma Sintering

Sun

Wang

et al. 2019

Crystal Research and Technology

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In this work, Ti-48Al-2Cr-8Nb alloy is sintered via spark plasma sintering with pre-alloyed powders prepared by the atomized method. The densification mechanism and microstructure evolution of the spark plasma sintered Ti-48Al-2Cr-8Nb alloy are analyzed. The sintering process is divided into two stages of densification and microstructure transformation. First, the densification mechanism of the powder materials at different sintering temperatures is investigated. At the beginning of the sintering process, the powder particles are closely rearranged under pressure. In the middle of the sintering process, the plastic deformation of the powder particles and the material migration between the adjacent particles promote the densification into the high-speed stage. In the late stages of sintering, the unique equilibrium phase transition of the TiAl alloy allows the densification to be completed quickly. Additionally, the formation process and phase transition mechanism of the near gamma structure, the duplex structure, the full-lamellar structure, and spherical structure in Ti-48Al-2Cr-8Nb alloy are systematically studied.

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“…Some of the implemented configurations, according to Witkin & Lavernia, are 101 attritor mills used at the University of California in Davis, charging up to 1kg of powder and the commercialised 35 kg capacity attritor mill sponsored by" Boeing's Rocketdyne division. Several recent studies [51][52][53][54] have been devoted to understanding the processing and behaviour of nanostructured TiAl alloys produced using CM and SPS. Shanmugasundaram et al [52], investigated the densification and microstructure of a γ-TiAl alloy produced using gas atomised CM powder and consolidated using SPS at 1050 and 1200 °C.…”

Section: Cryomilling (Cm)mentioning

confidence: 99%

“…The obtained refined microstructure (with grain sizes of 0.9 and 0.6 μm at 1200 and 1050 °C) consisted of γ and α2, with volume fraction of the later found to be dependent on the sintering temperature and O content. Deng et al [51] obtained an ultrafine-grained FL and near γ microstructure promoted by CM and varying sintering Several recent studies [51][52][53][54] have been devoted to understanding the processing and behaviour of nanostructured TiAl alloys produced using CM and SPS. Shanmugasundaram et al [52], investigated the densification and microstructure of a γ-TiAl alloy produced using gas atomised CM powder and consolidated using SPS at 1050 and 1200 • C. CM resulted in a 100% powder yield, reduced particle (2-50 µm) and crystalline sizes (40 nm).…”

Section: Cryomilling (Cm)mentioning

confidence: 99%

“…Deng et al [51] obtained an ultrafine-grained FL and near γ microstructure promoted by CM and varying sintering Several recent studies [51][52][53][54] have been devoted to understanding the processing and behaviour of nanostructured TiAl alloys produced using CM and SPS. Shanmugasundaram et al [52], investigated the densification and microstructure of a γ-TiAl alloy produced using gas atomised CM powder and consolidated using SPS at 1050 and 1200 • C. CM resulted in a 100% powder yield, reduced particle (2-50 µm) and crystalline sizes (40 nm). Although the alloy fully densified at 1200 • C, 8 h of CM resulted in a decrease in the sintering temperature.…”

Section: Cryomilling (Cm)mentioning

confidence: 99%

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Spark Plasma Sintering of Titanium Aluminides: A Progress Review on Processing, Structure-Property Relations, Alloy Development and Challenges

Mogale

Matizamhuka

2020

Metals

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Titanium aluminides (TiAl) have the potential of substituting nickel-based superalloys (NBSAs) in the aerospace industries owing to their lightweight, good mechanical and oxidation properties. Functional simplicity, control of sintering parameters, exceptional sintering speeds, high reproducibility, consistency and safety are the main benefits of spark plasma sintering (SPS) over conventional methods. Though TiAl exhibit excellent high temperature properties, SPS has been employed to improve on the poor ductility at room temperature. Powder metallurgical processing techniques used to promote the formation of refined, homogeneous and contaminant-free structures, favouring improvements in ductility and other properties are discussed. This article further reviews published work on phase constituents, microstructures, alloy developments and mechanical properties of TiAl alloys produced by SPS. Finally, an overview of challenges in as far as the implementation of TiAl in industries of interest are highlighted.

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On grain refinement of a γ-TiAl alloy using cryo-milling followed by spark plasma sintering

Cited by 26 publications

References 46 publications

Densification of Ni and TiAl by SPS: Kinetics and Microscopic Mechanisms

Densification of Ni and TiAl by SPS: Kinetics and Microscopic Mechanisms

Densification Mechanism and Microstructure Evolution of Ti‐48Al‐2Cr‐8Nb Alloy by Spark Plasma Sintering

Spark Plasma Sintering of Titanium Aluminides: A Progress Review on Processing, Structure-Property Relations, Alloy Development and Challenges

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