Positron Annihilation Characteristics in Perfect and Imperfect Transition Metal Carbides and Nitrides

Puska, Martti J.; Sob, M; Bräuer, G.; Korhonen, T.

doi:10.1051/jp4:1995115

Cited by 9 publications

(2 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Although the composition of TiC is almost stoichiometric, 9) a few carbon vacancies may be contained and work as strong trap sites. On the other hand V4C3 has almost 25% carbon vacancies 10) based on the stoichiometric number.…”

Section: Trap State At Interstitial Site Carbon Vacancy Andmentioning

confidence: 99%

Numerical Analysis of Hydrogen Trap State by TiC and V4C3 in bcc-Fe

Kawakami

Matsumiya

2012

ISIJ Int.

View full text Add to dashboard Cite

Hydrogen trap states by TiC and V4C3 precipitates in bcc-Fe are investigated by numerical calculations. The trap states at interstitial site and, carbon vacancy in metal carbide and bcc-Fe/metal-carbide interface were studied by ab-initio calculation. The calculated trap energies of these sites for TiC compared with the energy at interstitial site in bcc-Fe were respectively -58 kJ/mol, 125 kJ/mol and 48 kJ/mol and those for V4C3 were respectively -106 kJ/mol, 116 kJ/mol and -6 kJ/mol. The activation energy of detrapping from an isolated carbon vacancy is estimated at 183 kJ/mol for TiC and at 222 kJ/mol for V4C3 from the difference of the calculated energy at carbon vacancy and that at interstitial site in metal carbide. Hydrogen trap energy in coherent strain field around of TiC and V4C3 coherent precipitates in bcc-Fe are also calculated by Finite Element Method (FEM). The calculated energies are respectively less than 29 kJ/mol and less than 15 kJ/mol. These results indicate the main trap site of TiC is TiC/bcc-Fe interface, because TiC contains few carbon vacancies and has large activation energy of detrapping at the sites. That of V4C3 is carbon vacancies because V4C3 contains abundant carbon vacancies and the activation energy of migration between the neighbored carbon vacancy sites is expected to be lower than the calculated value . The estimated main trap sites of TiC is in good agreement with 3 Dimensional Atom Prove (3D-AP) observation results which reported that hydrogen atoms observed at TiC/bcc-Fe interface of TiC precipitate in bcc-Fe.

show abstract

Section: Trap State At Interstitial Site Carbon Vacancy Andmentioning

confidence: 99%

Numerical Analysis of Hydrogen Trap State by TiC and V4C3 in bcc-Fe

Kawakami

Matsumiya

2012

ISIJ Int.

View full text Add to dashboard Cite

show abstract

“…The first lifetime component seems to be a mixture of signals of different origins. Dislocations have lifetimes between 140 and 165 ps 9 and carbide precipitations between 130 and 180 ps 10 . Thus it appears that both dislocations and precipitations [V(C,N), Mo 2 C, Fe 3 C] exist in densities high enough to trap a noticeable fraction of positrons 7…”

Section: Resultsmentioning

confidence: 99%

Creep‐damaged pipe steels probed with positron spectroscopy

Somieski

Krause‐Rehberg

2001

Fatigue Fract Eng Mat Struct

View full text Add to dashboard Cite

Using positron lifetime spectroscopy (POLIS) the degree of damage in creep-influenced pipe steels was found to decrease with depth, as measured from the physical surface of the samples. Ultrasonic measurements were revealed to mostly note the differences in internal stresses, not in the microstructure. A critical limit of 160 ps average positron lifetime was determined at about 80% of material lifetime consumption in a creep experiment, independent of the material or the creep test parameters. The results suggest the technique of positron lifetime spectroscopy as a method for nondestructive monitoring of creep damage

show abstract

New Route to Synthesize High-Entropy Carbide Powders by Mechanical Alloying

Idczak,

Sobota,

Tran

et al. 2023

Metall Mater Trans A

View full text Add to dashboard Cite

A new route for the synthesis of the (NbTa)$$_{0.67}$$ 0.67 (TiHfZr)$$_{0.33}$$ 0.33 C and (NbTa)$$_{0.67}$$ 0.67 (MoHfW)$$_{0.33}$$ 0.33 C high-entropy carbides powders by mechanical alloying is presented. Namely, pure metal powders were wet-milled in toluene using a planetary mill under an argon atmosphere. The synthesized materials crystallize with a rock-salt structure (space group $$Fm{\bar{3}}m$$ F m 3 ¯ m ). A significant reduction in structural defects with annealing of the samples was detected with X-ray diffraction and positron annihilation experiments. Simultaneously, only simple metallic properties without any trace of magnetic or superconducting phase transitions were observed.

show abstract

Positron Annihilation Characteristics in Perfect and Imperfect Transition Metal Carbides and Nitrides

Cited by 9 publications

References 4 publications

Numerical Analysis of Hydrogen Trap State by TiC and V4C3 in bcc-Fe

Numerical Analysis of Hydrogen Trap State by TiC and V4C3 in bcc-Fe

Creep‐damaged pipe steels probed with positron spectroscopy

New Route to Synthesize High-Entropy Carbide Powders by Mechanical Alloying

Contact Info

Product

Resources

About