High‐pressure sintering of ultrafine‐grained high‐entropy diboride ceramics

Bulk ultrafine-grained (UFG) materials usually show superior mechanical and physical properties. The development of micro-mechanical behavior is observed after significant changes in microstructure through high-pressure torsion (HPT) processing. This report summarizes recent results on the evolution of small-scale mechanical response examined by the nanoindentation technique on two UFG materials including a high-entropy alloy and an Al-Mg metal matrix nanocomposite processed by HPT. Special emphasis is placed on demonstrating the interrelationship of essential microstructural changes with increasing torsional strain and applying a post-deformation annealing treatment and the evolution of the micro-mechanical behavior in these UFG materials by estimating the strain rate sensitivity.

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High-Pressure Torsion for Synthesis of High-Entropy Alloys

Metals ◽

10.3390/met11081263 ◽

2021 ◽

Vol 11 (8) ◽

pp. 1263

Author(s):

Kaveh Edalati ◽

Hai-Wen Li ◽

Askar Kilmametov ◽

Ricardo Floriano ◽

Christine Borchers

Keyword(s):

High Pressure ◽

High Pressure Torsion ◽

High Light ◽

Metallic Alloys ◽

High Entropy Alloys ◽

Hydrogen Storage Properties ◽

High Entropy ◽

Ultrafine Grained ◽

Light Absorbance ◽

Storage Properties

High-pressure torsion (HPT) is widely used not only as a severe plastic deformation (SPD) method to produce ultrafine-grained metals but also as a mechanical alloying technique to synthesize different alloys. In recent years, there have been several attempts to synthesize functional high-entropy alloys using the HPT method. In this paper, the application of HPT to synthesize high-entropy materials including metallic alloys, hydrides, oxides and oxynitrides for enhanced mechanical and hydrogen storage properties, photocatalytic hydrogen production and high light absorbance is reviewed.

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Micro-Mechanical Responses of Ultrafine-Grained Materials Processed through High-Pressure Torsion

Materials Science Forum ◽

10.4028/www.scientific.net/msf.879.42 ◽

2016 ◽

Vol 879 ◽

pp. 42-47 ◽

Cited By ~ 1

Author(s):

Megumi Kawasaki ◽

Jae Il Jang ◽

Byung Min Ahn ◽

Terence G. Langdon

Keyword(s):

High Pressure ◽

High Pressure Torsion ◽

Rate Sensitivity ◽

Small Scale ◽

High Entropy Alloy ◽

High Entropy ◽

Mechanical Responses ◽

Ultrafine Grained ◽

Mechanical And Physical Properties ◽

Zk60 Magnesium Alloy

The processing of metals through the application of high-pressure torsion (HPT) provides the potential for achieving exceptional grain refinement in bulk metal solids. These ultrafine grains in the bulk metals usually show superior mechanical and physical properties. Especially, the development of micro-mechanical behavior is observed after significant changes in microstructure through processing and it is of great importance for obtaining practical future applications of these ultrafine-grained metals. Accordingly, this presentation demonstrates the evolution of small-scale deformation behavior through nanoindentation experiments after HPT on various metallic alloys including a ZK60 magnesium alloy, a Zn-22% Al eutectoid alloy and a high entropy alloy. Special emphasis is placed on demonstrating the essential microstructural changes of these materials with increased straining by HPT and the evolution of the micro-mechanical responses in these materials by measuring the strain rate sensitivity.

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Microstructural Study of Diamond Deformed Under High Pressure and Temperature

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100118072 ◽

1985 ◽

Vol 43 ◽

pp. 230-231

Author(s):

E. F. Koch

Keyword(s):

High Pressure ◽

High Temperature ◽

Lattice Structure ◽

Diamond Particle ◽

Polycrystalline Diamond ◽

Sintering Process ◽

Ion Milling ◽

Sintered Compact ◽

Transmission Electron ◽

High Pressure Sintering

Because of the extremely rigid lattice structure of diamond, generating new dislocations or moving existing dislocations in diamond by applying mechanical stress at ambient temperature is very difficult. Analysis of portions of diamonds deformed under bending stress at elevated temperature has shown that diamond deforms plastically under suitable conditions and that its primary slip systems are on the ﹛111﹜ planes. Plastic deformation in diamond is more commonly observed during the high temperature - high pressure sintering process used to make diamond compacts. The pressure and temperature conditions in the sintering presses are sufficiently high that many diamond grains in the sintered compact show deformed microtructures.In this report commercially available polycrystalline diamond discs for rock cutting applications were analyzed to study the deformation substructures in the diamond grains using transmission electron microscopy. An individual diamond particle can be plastically deformed in a high pressure apparatus at high temperature, but it is nearly impossible to prepare such a particle for TEM observation, since any medium in which the diamond is mounted wears away faster than the diamond during ion milling and the diamond is lost.

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