Metallography and Microstructures of Powder Metallurgy Alloys

Pease, Leander F.; Pease, Douglas L.

doi:10.31399/asm.hb.v09.a0003789

Cited by 4 publications

(3 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Samples were ground using wet grit SiC paper of 600-800-1200-2400-4000, respectively, for one minute at a force of 20 N. The specimens were polished with diamond suspension solution of 6 µm, 3 µm, and 1 µm for 10 min in each step, applying a force of 20 N, and finally finishing with colloidal dispersions of silica (SiO 2 ) for 10 min. The procedures were applied according to ASTM-B215, using standard metallographic methods for uncompacted metal powders [47]. The shape, microstructure and SDAS of the powders were investigated by using an Ultra Plus Field Emission Scanning Electron Microscope (SEM).…”

Section: Powder Characterizationmentioning

confidence: 99%

Cooling Rate Modeling and Evaluation during Centrifugal Atomization Process

Cegarra

Pijuan

Riera

2023

JMMP

View full text Add to dashboard Cite

Centrifugal atomization is a rapid solidification technique involving fast cooling rates to produce high-quality powders. The final microstructure of the atomized particles is closely linked with the thermal history and cooling rates experienced during the atomization process. However, there is insufficient research on the temperature evolution of metal particles produced by this technique, and most works evaluate the thermal history of the droplet through semi-empirical correlations that lie outside the conditions where they were derived. In this work, the cooling rate of centrifugally atomized Al-4% Cu was studied via mathematical modelling and experimental validation. A heat transfer model was implemented, and the value of the convective heat transfer coefficient was obtained from the Whitaker semi-empirical correlation considering three cases of study for the thermophysical properties of the gas. The validity of the Whitaker correlation was experimentally evaluated by means of cooling rates based on the Secondary Dendrite Arm Spacing (SDAS) technique. The Whitaker correlation with the Reynolds and Prandtl numbers evaluated at the ambient temperature and the gas conductivity evaluated at the film temperature gave the best agreement with the experimental results, with cooling rates in the order of 105 K s−1 for <32.5 µm powders atomized in He atmosphere.

show abstract

Section: Powder Characterizationmentioning

confidence: 99%

Cooling Rate Modeling and Evaluation during Centrifugal Atomization Process

Cegarra

Pijuan

Riera

2023

JMMP

View full text Add to dashboard Cite

show abstract

“…Close reading hunts out verbal language’s ‘body language’—the things that people may seek to hide yet nevertheless can reveal through their word choices, sequencing, omissions, repetitions, euphemisms, emphases and de-emphases (van Dijk, 2016). As with body language, we should interpret elements in context and within clusters, not in isolation, and look for patterns of congruence or dissonance (Pease and Pease, 2004). The examples in sections 4 and 5 will point to this.…”

Section: The Importance Of ‘Making Strange’ and The Role For Structur...mentioning

confidence: 99%

‘Making Strange’: Discourse Analysis Tools for Teaching Critical Development Studies

Gasper¹

2022

Progress in Development Studies

View full text Add to dashboard Cite

Critical development studies require not just a critical attitude, but also usable tools. This article suggests some forms of discourse analysis that can add substance to critical development studies’ aspirations and that can yet be learnt and used by students without specialist background. Central are tools for ‘making strange’ (defamiliarization), so that we view both texts and social realities in a fresh independent way and start to discern better their blindspots, and our own. The article presents accessible yet helpful forms of text analysis, argumentation analysis and content analysis that contribute in required processes of defamiliarization and reconstruction.

show abstract

“…The particles were then embedded in cold-mounting resin, ground, and polished with diamond suspension solution and finished with a colloidal dispersion of silica (SiO 2 ) using standard metallographic methods for uncompacted metal powders [27]. The surface morphology and microstructure of the powders were investigated using an Ultra Plus fieldemission scanning electron microscope (SEM).…”

Section: Powder Characterizationmentioning

confidence: 99%

Centrifugal Atomization of Glass-Forming Alloy Al86Ni8Y4.5La1.5

et al. 2022

View full text Add to dashboard Cite

Centrifugal atomization is a rapid solidification technique for producing metal powders. However, its wide application has been limited to the production of common metal powders and their corresponding alloys. Therefore, there is a lack of research on the production of novel materials such as metallic glasses using this technology. In this paper, aluminum-based glassy powders (Al86Ni8Y4.5La1.5) were produced by centrifugal atomization. The effects of disk speed, atomization gas, and particle size on the cooling rate and the final microstructure of the resulting powder were investigated. The powders were characterized using SEM and XRD, and the amorphous fractions of the atomized powder samples were quantified through DSC analysis. A theoretical model was developed to evaluate the thermal evolution of the atomized droplets and to calculate their cooling rate. The average cooling rate experienced by the centrifugally atomized powder was calculated to be approximately 7 × 105 Ks−1 for particle sizes of 32.5 μm atomized at 40,000 rpm in a helium atmosphere. Amorphous fractions from 60% to 70% were obtained in particles with sizes of up to 125 μm in the most favorable atomization conditions.

show abstract

Metallography and Microstructures of Powder Metallurgy Alloys

Cited by 4 publications

References 3 publications

Cooling Rate Modeling and Evaluation during Centrifugal Atomization Process

Cooling Rate Modeling and Evaluation during Centrifugal Atomization Process

‘Making Strange’: Discourse Analysis Tools for Teaching Critical Development Studies

Centrifugal Atomization of Glass-Forming Alloy Al86Ni8Y4.5La1.5

Contact Info

Product

Resources

About