Structure and properties of fine metallic particles

Morokhov, I.D.; Petinov, V.I.; Трусов, Л. И.; Петрунин, В. Ф.

doi:10.3367/ufnr.0133.198104c.0653

Cited by 93 publications

(15 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Various defects accumulate, mainly in the subsurface and grain-boundary regions of the dispersed particles. This increases the free energy of the titanium hydride particles [2] and consequently reduces the decomposition temperature, i.e., reduces the thermal stability. The higher the degree of dispersal in these particles from mechanical treatment, the more extremely disordered regions there are with maximal numbers of defects, and the greater the energy stored in them [3,4] which means that there is an increased number of hydrogen atoms that receive part of this stored energy from the hydride lattice, and they leave it on heating and decomposition at a lower temperature.…”

Section: Resultsmentioning

confidence: 98%

Effects of dispersal and mechanical boron alloying on the thermal stability of hydride phases in the Ti-B-H system

Dobrovol'skii

Radchenko

Solonin

et al. 2006

Powder Metall Met Ceram

View full text Add to dashboard Cite

621.762Methods have been applied from scanning electron microscopy, hydrogen thermal desorption, XRD, and differential thermal analysis on the effects of grain size and alloying with boron as regards the thermal stability and decomposition temperatures of hydride phases in mechanical alloys in the Ti − B − H system. The alloys were prepared by high-energy processing for 50 h in a planetary ball mill with mixtures of TiH 1.9 + 9 mass% B + 13 mass% Ti and also with TiH 1.9 + 50 mass% TiB 2 at speeds of 1000 rpm, in addition to mixtures of TiH 1.9 + 40 mass% B and TiH 1.9 + 50 mass% TiB 2 , which were treated for 20 min at speeds of 1680 rpm. The dispersal on mechanical treatment and the addition of boron to the titanium hydride powder have substantial effects on the thermal stability. The processing of the mixture TiH 1.9 + 9 mass% B + 13 mass% Ti lasting 50 h in argon gave temperatures for the dissociation of the Ti(B, H) x hydride phase in the mechanical alloy lower by 300 deg than the decomposition temperature for the initial titanium hydride TiH 1.9 . The mechanisms have been identified for the effects of the dispersal and boron alloying on the thermal stability of the titanium hydride.

show abstract

Section: Resultsmentioning

confidence: 98%

Effects of dispersal and mechanical boron alloying on the thermal stability of hydride phases in the Ti-B-H system

Dobrovol'skii

Radchenko

Solonin

et al. 2006

Powder Metall Met Ceram

View full text Add to dashboard Cite

show abstract

“…So, mechanical alloys 1 and 3 differ in the degree of dispersion of their particles. It is known [11][12][13] that small particles produced due to mechanical dispersion may possess excess energy and entropy, which cause the phase equilibrium to shift. In the case of mechanical alloy 2, which has the same low degree of particle dispersion as specimen 1, lowering of decomposition temperature of its hydride is not observed in spite of the presence of iron in the alloy.…”

Section: Resultsmentioning

confidence: 99%

“…In our view, the hydrogen with medium bond in the hydride phase of mechanical alloy 3 is concentrated primarily in the region of grain boundaries, the amount of which, like the amount of defects in this region, rises with rise in the degree of dispersion of the powders as the time of their milling in the ball mill increases. Accumulation of defects in this region is accompanied by an increase in the thermodynamic potential of this the most deformed, dispersed, and disordered region on account of deformation work and formation of new surfaces [11][12][13], which indeed causes lowering of the decomposition temperature of the hydride phase and, consequently, lowering of its thermal stability.…”

Section: Resultsmentioning

confidence: 99%

Thermal stability of hydride phase obtained by mechanical treatment of Mg-10 mass% Fe in hydrogen under pressure

Dobrovol'skii

Radchenko

Solonin

et al. 2006

Powder Metall Met Ceram

View full text Add to dashboard Cite

621.762The formation of hydride phases under high-energy ball-milling of Mg and Mg + 10 mass% Fe powders in hydrogen under a pressure of 1.2 MPa has been studied. The influence of iron content and dispersion degree of the Mg-alloys upon thermal stability and decomposition temperature of the hydride phase of the alloys was investigated by thermal desorption, x-ray diffraction, and differential thermal analyses. It was established that addition of 10 mass% of iron to magnesium contributes to higher dispersion degree of the magnesium hydride obtained via milling in hydrogen under pressure. The hydride contains maximum amount of weak-and medium-bound hydrogen. The latter is mainly concentrated in the region of grain boundaries, the quantity of which increases with increase in dispersion degree. The formation of new boundaries and accumulation of defects in these regions are accompanied by an increase in thermodynamic potential, which causes a decrease in both the temperature of decomposition of the hydride phase by 100°C and its thermal stability.

show abstract

“…As a result, a great quantity of different defects occurs mainly in near-surface and grain-boundary areas of dispersive particles. This causes an increase of free (Helmholtz) energy of titanium hydride particles [7] and, as a consequence, a decrease of decomposition temperature of the hydride (i.e., a decrease of its thermal stability). The higher a degree of dispersion of particles of the hydride phase in the result of its mechanical treatment, the greater amount of extremely disordered areas where defects accumulate and, as a result, the higher energy accumulated in these areas [8,9].…”

Section: Resultsmentioning

confidence: 99%

Mechanical alloys in the Ti–B–H system: Influence of dispersion and alloying by boron upon thermal stability of hydride phases

Dobrovolsky

Ershova

Solonin

2011

Journal of Alloys and Compounds

View full text Add to dashboard Cite

Structure and properties of fine metallic particles

Cited by 93 publications

References 9 publications

Effects of dispersal and mechanical boron alloying on the thermal stability of hydride phases in the Ti-B-H system

Effects of dispersal and mechanical boron alloying on the thermal stability of hydride phases in the Ti-B-H system

Thermal stability of hydride phase obtained by mechanical treatment of Mg-10 mass% Fe in hydrogen under pressure

Mechanical alloys in the Ti–B–H system: Influence of dispersion and alloying by boron upon thermal stability of hydride phases

Contact Info

Product

Resources

About