Subsurface deformation during Vickers indentation of bulk metallic glasses

Bonded interface technique was employed to examine the nature of subsurface deformation during Vickers indentation in two kinds of bulk metallic glasses (BMGs), Pd42.1Ni39.77P18.13, and Zr56.69Cu26.96Al10.95Ni5.4. Quantitative information such as the shear band spacing, pile-up length, subsurface deformation zone size etc. was recorded for indentation loads ranging from 50 to 5000 g. Experimental results show that both the BMGs have an average hardness value of ~550 VHN with slightly higher hardness at low loads. Observations of deformation zones indicate that they deform appreciably through the shear band mechanism. For both bulk indentation, as well as the interface indentation, the normalized size of the deformation zone was found to be independent of the applied load. Two types of shear bands, radial, and semi-circular in nature, have been observed. These results are compared with similar studies made on ductile metals and silicate glasses

Hardness and plastic deformation in a bulk metallic glass

An experimental investigation into the Vickers hardness and associated plastic deformation in as-cast and annealed Pd42Ni40P18 bulk metallic glass was conducted. In addition to the bulk indentation behavior, the deformation morphology underneath the indenter and its variation with annealing time was examined by employing the bonded interface technique. For both the bulk and the interface indentations, the trends in the shear band induced plastic deformation zone sizes with the indentation load agree well with those predicted from the expanding cavity model. However, the yield strength extracted from the indentation data is higher than that measured in uniaxial compression, indicating pressure sensitive plasticity. Results show that the as-cast as well as the partially crystallized alloys deform appreciably through the shear band mechanism, with semi-circular and radial shear band morphologies. The latter gets increasingly prominent with increasing annealing time. Atomic force microscopy of the deformation region reveals increasing shear band heights with load, consistent with nanoindentation results. Whereas the spacing between semicircular shear bands was found to be independent of their distance from the tip of the indenter for the as-cast alloy, it was found to increase linearly, after a small zone of constant spacing, in the annealed alloys. Implications of this study in understanding the mechanical behavior of metallic glasses and their derivatives are discussed

Recycling and Treatment of Settling Pond Fines - A challenge to Industry and Environment

About 3.0 Million tonness of coking coal fines (-0.5mm) generated from various coal preparation plants are lying in the lagoons/settling ponds in the vicinity of these plants for quite some time . In addition, 60,0001t of slurries are being bled every month to these waste basins. These discarded coal fines which contain significant amount of vitrinite enriched coking materials, are not being properly utilised due to the following reasons. (i)Inability of existing coal washing circuit to benef- iciate these coal fines from the slurry economically ii) Environmental restrictions regarding waste disposal were not stringent; (iii) Non-availability of suit- able technology to recover the coal fines at desired quality. To use these coal slurry fines, CFRI through decades long R&D efforts have developed an improved process technology, which can recover finest cleans (ash < 15%) from the said high ash (30-35%) coal slurry. Based on CFRI to Tech-nology, three mini flotation plants have been commissioned of throughput capacity 5 to 10 tph in small scale sector, which are successfully producing cleans (Yield 50-60%, and Moisture < 20%) from high ash coal slurry and dispatching the low ash cleans to M/s IISCO. Burnpur as one of their coking blend constituents for metallurgical coke making. Many irety mini flotation plants are coming into picture based upon this technology. This paper summarises data, concerning slurry pond quality estimate, floatability, material recovery, etc

Deformation morphology underneath the vickers indent in a Zr-based bulk metallic glass

Hardness and plastic deformation during Vickers indentation in as-cast, annealed, and fully crystallized Zr57Cu27Al11Ni5 bulk metallic glass was examined. Subsurface deformation morphology under the indenter tip was studied at various loads and for different annealing time. Appreciable plastic deformation, through shear banding, occurs in the as-cast and annealed alloys. Two different types of shear bands are observed. Their occurrence depends upon the amount of annealing and hence on the extent of crystallization. The fully crystallized alloy exhibits extensive cracking. Trends in the deformation zone size with load are consistent with the expanding cavity model, while the shear band morphology, particularly for the as-cast sample, attests the qualitative applicability of the slip line field theory

Estimates of genetic parameters of fruit quality traits in teasle gourd (Momordica subangulata Blume. subsp. renigera)

The present investigation was carried out to assess genetic variability, heritability and genetic advance in five genotypes of teasle gourd. The experiment was laid out in a randomized block design with four replications. High phenotypic coefficients of variation were observed for all characters except ascorbic acid in excoarp, ascorbic acid in mesocarp, total soluble solids (TSS) in exocarp, b-carotene in exocarp, acidity in mesocarp, b-carotene in mesocarp, TSS in mesocarp, acidity in exocarp which showed high heritability coupled with high genetic advance indicating that these traits were gene control and simple phenotypic selection can be used for further improvement of these traits. Fruit weight, which showed the highest positive direct effect on fruit yield also showed positive correlation with β-carotene in exocarp. The most important fruit quality influencing traits from the study includes TSS content of exocarp and mesocarp since these traits character showed positive correlations with most important fruit quality characters.Keywords: Teasle gourd, clones, variability, heritability, genetic advance, correlation coefficientAfrican Journal of Biotechnology, Vol. 13(2), pp. 257-264, 8 January, 201

Higgsino Dark Matter in a SUGRA Model with Nonuniversal Gaugino Masses

We study a specific SUGRA model with nonuniversal gaugino masses as an alternative to the minimal SUGRA model in the context of supersymmetric dark matter. The lightest supersymmetric particle in this model comes out to be a Higgsino dominated instead of a bino dominated lightest neutralino. The thermal relic density of this Higgsino dark matter is somewhat lower than the cosmologically favoured range, which means it may be only a subdominant component of the cold dark matter. Nonetheless, it predicts favourable rates of indirect detection, which can be seen in square-km size neutrino telescopes.Comment: Version to appear in Phys. Rev. D. A few references added in the bibliography and a comment added in Section 2. LaTex, 16 pages, 4 figure

Density Evolution in the New Modified Chaplygin Gas Model

In this paper, we have considered new modified Chaplygin gas (NMCG) model which interpolates between radiation at early stage and $\Lambda$CDM at late stage. This model is regarded as a unification of dark energy and dark matter (with general form of matter). We have derived the density parameters from the equation of motion for the interaction between dark energy and dark matter. Also we have studied the evolution of the various components of density parameters.Comment: 6 Latex pages, 4 figures, RevTex styl

The LHC (CMS) Discovery Potential for Models with Effective Supersymmetry and Nonuniversal Gaugino Masses

We investigate squark and gluino pair production at LHC (CMS) with subsequent decays into quarks, leptons and LSP in models with effective supersymmetry where third generation of squarks is relatively light while the first two generations of squarks are heavy. We consider the general case of nonuniversal gaugino masses. Visibility of signal by an excess over SM background in (n \geq 2)jets + (m \geq 0)leptons + E^{miss}_T events depends rather strongly on the relation between LSP, second neutralino, gluino and squark masses and it decreases with the increase of LSP mass. We find that for relatively heavy gluino it is very difficult to detect SUSY signal even for light 3^{rd} generation squarks (m_{\tilde q_3}\le 1 TeV) if the LSP mass is closed to the 3^{rd} generation squark mass.Comment: 1 latex (35 pages), 4 eps (figures) file

A study of generalized second law of thermodynamics in modified f(R) Horava-Lifshitz gravity

This work investigates the validity of the generalized second law of thermodynamics in modified f(R) Horava-Lifshitz gravity proposed by Chaichian et al (2010) [Class. Quantum Grav. 27 (2010) 185021], which is invariant under foliation-preserving diffeomorphisms. It has been observed that the equation of state parameter behaves like quintessence (w > -1). We study the thermodynamics of the apparent, event and particle horizons in this modified gravity. We observe that under this gravity, the time derivative of total entropy stays at positive level and hence the generalized second law is validated.Comment: 12 pages, 8 figures, Accepted for publication Astrophysics and Space Science, 201