Massive Grains Research Articles

Strengthening, strain hardening and fracture of heat-treated interstitial-free steel with massive ferrite conceptualizing the interface controlled reaction phenomena

Interstitial-free steel is extremely soft and ductile with allotriomorphic ferrite in the microstructure as a diffusional transformation product of austenite. In order to alter the mechanical property, the present work performed austenitization of the steel at 925 °C for 5 min and thereafter a rapid water quenching, resulting in massive ferrite. The yield strength (86 MPa) and ultimate tensile strength (181 MPa) increased to 362 MPa and 531 MPa, respectively, along with 18 % ductility. The statistically stored dislocation density and substructures (sub-boundaries, cells) at the grain body contributed 68 % of the yield strength. The strain hardening was observed to be lower than that with allotriomorphic ferrite, due to heterogeneous deformation of the substructures, causing an inhomogeneous distribution of geometrically necessary dislocation density at the bulk. The preferential localization of strain at cell walls initiates cracks by the de-cohesion of massive grains. The cell-substructure conceived by massive ferrite therefore has a strong role both in strain hardening and fracture. The larger the grain size is, the more the cell-substructure is, dictated by an interface-controlled growth of austenite to massive ferrite. The atomic jump at the transformation interface is usually considered to be an equilibrium process; meaning slow, not standing with the so-called faster growth kinetics of an interface-controlled reaction. In order to bridge the gap, the present work demonstrates a slip deformation at the transformation interfaces for fast-tracking the lattice reconstruction of massive ferrite from austenite, a novel.

Massive transformation in dual-laser powder bed fusion of Ti6Al4V alloys

In the present investigation, we fabricated additively manufactured Ti6Al4V parts using dual laser-powder bed fusion (DL-PBF) and identified the occurrence of a massive transformation. A detailed and systematic study of the massive transformation in the DL-PBF process by changing the energy and time offset of the lag laser beam and its effect on the microstructural and mechanical properties was undertaken. A mixture of martensite and massive phases was observed within the prior β grains in DL-PBF, and the dimensions of these massive grains increased with an increase in the lag laser beam energy, while acicular α′ martensite was present in the single Laser-PBF. The massive phase showed a featureless patch-shaped region, which consisted of thin laths, and they were associated with the prior β grain boundaries. The irregular patch-shaped regions showed inferior Vickers hardness when compared with acicular α′ martensite, and the ultimate tensile strength was lower in the DL-PBF than in the single Laser-PBF. The columnar prior-β grain was present in all the samples (both in the single- and dual-beam laser) and the dimensions of the grains varied with increasing the lag laser beam energy. These present results showed that the DL-PBF process significantly influenced the microstructural and mechanical properties of the Ti6Al4V materials, and provided a deep insight into massive phase transformation in AM titanium alloys and its effect on the mechanical properties.

Landau damping effects on dust ion-acoustic solitary waves in a nonthermal pair-ion plasma

The Landau damping effects on the nonlinear propagation of dust ion-acoustic solitary waves (DIASWs) are studied in an electron-free unmagnetized collisionless dusty pair-ion plasma. The two species of nonthermal ions (positive and negative) are described by the kinetic Vlasov equations, whereas the massive charged dust grains form only the background plasma. Using the multi-scale reductive perturbation technique generalized for the applications to the Vlasov equation, we derive a modified Korteweg–de Vries (KdV) equation that governs the evolution of DIASWs with the effects of linear resonance, in particular, linear Landau damping. The properties of the phase velocity and the Landau damping rate of DIASWs are studied with the effects of positive and negative-ion nonthermality parameters ( α p , α n ), the ratios of the positive to negative ion masses (m) and temperatures (T) as well as the dust to negative-ion number density ratio (δ). It is found that, depend on the degree of positive to negative ion mass ratios (m), both of damped and growing oscillations occur in a collisionless dusty pair-ion plasma due to the resonance phenomena between the wave and the nonthermal particles of the system. The properties of the decay rates of the amplitude of the KdV soliton with a small effect of Landau damping are also studied with the above system of parameters. The results may be useful for understanding the localization of solitary pulses and associated resonance damping and/or growing oscillations of the wave in laboratory and space plasmas, in which the number density of free electrons is much smaller than that of ions and highly charged heavy, micron seized dust grains.

Genesis of the Beizhan Iron Deposit in Western Tianshan, China: Insights from Trace Element and Fe-O Isotope Compositions of Magnetite

The Beizhan iron deposit (468 Mt at an average grade of 41% Fe) is the largest iron deposit in the Awulale iron metallogenic belt of Western Tianshan, northwest China. The high-grade magnetite ores are hosted in the Carboniferous volcanic rocks with extensive development of skarn alteration assemblages. While considerable progress has been made in understanding the characteristics of Beizhan and its genetic association with volcanic rocks, the genetic models for ore formation are poorly constrained and remain controversial. This study combines detailed petrographic investigations with in situ LA-ICP-MS analyses of trace elements and Fe-O isotope compositions of magnetite to elucidate the origin of magnetite and the conditions of ore formation. The trace element concentrations in magnetite unveil intricate origins for various ore types, implying the precipitation of magnetite from both magmatic and hydrothermal fluids. The application of the Mg-in magnetite thermometer (TMg-mag) reveals a notable temperature divergence across different magnetite varieties, spanning from relatively higher temperatures in magmatic brecciated magnetite (averaging ~641 and 612 °C) to comparatively lower temperatures in hydrothermal platy magnetite (averaging ~552 °C). The iron isotopic composition in massive and brecciated magnetite grains, characterized by lighter δ56Fe values (ranging from −0.078 to +0.005‰ and −0.178 to −0.015‰, respectively), suggest a magmatic or high-temperature hydrothermal origin. Conversely, the heavier δ56Fe values observed in platy magnetite (+0.177 to +0.200‰) are attributed to the influence of pyrrhotite, signifying late precipitation from low-temperature hydrothermal fluids. Additionally, the δ18O values of magnetite, ranging from +0.6 to +4.6‰, provide additional evidence supporting a magmatic–hydrothermal origin for the Beizhan iron deposit. Overall, the identified genetic associations among the three magnetite types at Beizhan provide valuable insights into the evolution of ore-forming conditions and the genesis of the deposit. These findings strongly support the conclusion that the Beizhan iron deposit underwent a process of magmatic–hydrothermal mineralization.

Nonlinear dust-acoustic wave dynamics in nonthermal Saturnian E-ring with negative ion moderation

The nonlinear stability dynamics of dust-acoustic waves (DAWs) near the plasma-active satellite of Saturn, Enceladus, is herein theoretically investigated in the perturbative framework. Enceladus being the source of the materials of Saturn's one of the most diffuse and wide E-ring, has a very active plasma environment rich in diversified collective dynamics of freedom. This theoretical model formalism is developed in the light of observations made by the Radio and Plasma Wave Science (RPWS) instrument inbuilt in the Cassini spacecraft in the vicinity of Enceladus. The model consists of electrons, positive ions, and negative ions obeying nonthermal kappa distribution laws. In contrast, the constitutive massive charged dust grains are treated as inviscid fluid. A standard method of multiple scaling technique is systematically employed to yield a Korteweg-de Vries (KdV) equation on the first-order electrostatic potential fluctuations. A constructed numerical platform demonstrates that such fluctuations evolve as a solitary pulse-train or solitary wave chain of rarefactive type. The results are further compared with solitary structures detected by RPWS during Cassini's closest approach to Enceladus. It is interestingly found that the bipolar electrostatic field amplitude of the derived dust-acoustic solitary pulses (4−11 mV/m) theoretically investigated here falls well within the range of observationally obtained field value (≥10 mV/m). Finally, the non-trivial wave amplitude growth features with diverse plasma multi-parametric variations are spotlighted illustratively.

Effects of biochar produced from distiller grains on agronomic performances of sorghum (Sorghum bicolor L.) and greenhouse gas emissions from soil

Aromatic liquor breweries produce massive distiller grains containing a high percentage of rice husks that necessitate harmless treatment and resource utilization. These husk-rich distiller grains can be pyrolyzed in the Ni-based catalyst system at a relatively low temperature (480 °C) into combustible gas, which is used in liquor distillation, and biochar (BDG) with high mineral nutrients and good surface properties. A 3-year field experiment (2018–2020) was established to understand the effects of BDG on sorghum agronomic performances and greenhouse gas emissions from the soil. The results showed that BDG had higher mineral nutrient (N, P, K, and S) contents, larger cation exchange capacity, and better surface structure than those prepared using the traditional method at 400 and 600 °C. Compared with sole chemical fertilizer (CF), the combination of CF and BDG (CF+BDG) increased sorghum nutrient (N, P, and K) uptake, yield, fertilizer use efficiency, and economic benefit. Cumulative CO2 emission from the soil changed little between with and without BDG, indicating the microbial stability of BDG. The effective adsorption of NH3 or NH4+ by BDG upon N application may reduce N loss through NH3 and N2O emissions and increase the efficiency of fertilizer N use. Cumulative CH4 emission ranged from 32.45 to 44.86 g ha-1, which could be overlooked as a greenhouse gas in the sorghum field. Moreover, CF+BDG significantly decreased NH3 and N2O emissions for the production of each unit of sorghum grains and the CO2 emission from the land for the production of a certain amount of sorghum grains. Therefore, CF+BDG exhibited better agronomic and environmental performances in sorghum cultivation.

Wave breaking amplitudes of Langmuir modes in electron-positron-ion-dusty plasmas

In contrast to the conventional studies on low frequency dust acoustic or dust ion acoustic waves, the investigation is done here on the wave characteristics of high frequency Langmuir modes in electron-positron-ion-dusty plasmas. In the wave analysis, the electrons, positrons, and ions are considered to follow relativistic dynamics. Whereas negative or positive polarity massive dust grains form a fixed charge neutralizing background. Within the Sagdeev pseudopotential approach, the wave breaking amplitudes of such high frequency oscillations are derived. The wave breaking amplitudes are shown to depend on various system parameters like equilibrium ion-to-electron density ratio, relativistic Lorentz factor associated with the phase velocity of oscillations, etc. It has been demonstrated that, even though the dust grains do not participate in the wave dynamics, the nature of their charge polarity and the values of equilibrium dust density have profound effects on the wave breaking amplitudes. We expect that the results of our investigation in such dusty plasma medium may have some relevance in the space plasma research.

The effect of cryogenic treatment on the microstructure and room-temperature mechanical properties of the (HEAp/Al) at different temperatures

At present, high entropy alloy particle reinforced aluminum matrix composites (HEAp/Al) have some shortcomings in performance. For example, it has high strength but low plasticity and processability. This paper mainly investigated how the different cryogenic temperature (−50 ℃, −100 ℃ and-196 ℃) affects the properties of (FeCoNi1.5CrCu)p/Al composites. When the cryogenic temperature drops, the maximum compression ratio (δ) and fracture energy of (FeCoNi1.5CrCu)p/Al composites enhances. The optimized − 196 ℃ sample exhibits the maximum δ of 25.21% and 5.31 × 107 J/m3 fracture energy that corresponds to high plasticity, toughness and Schmidt factor (SF). It also reaches the maximum nano-indentation and elastic modulus in the inter-diffusion layer. The enhancement of performance is attributed to its high compactness, fine HEA particles, nanometer-sized Cr precipitates around HEAP. After DCT, we can find that refined grains, massive high-angle boundary grains, induced texture are connected with the recrystallization and free energy. But those positive factors are counteracted by the significant decrease of dislocation density, which directly results in the decrease of compression strength.

Microstructure and mechanical properties of medium manganese steel in intercritical annealing

A new type of cold-rolled medium manganese steel was investigated. The test steel was treated by Q&P process. With the increase in annealing temperature, the grain size gradually increases, the carbides dissolve progressively and the fine lath grains transform into massive or equiaxed grains. Both the volume fraction and the stability of the retained austenite are continuously decreasing, which together affect the change of mechanical properties. At the intercritical annealing temperature of 680°C, the specimens have higher retained austenite content and transformation rate. At the same time, due to the discontinuous TRIP effect caused by the retained austenite stability gradient inside the specimen, it exhibits excellent comprehensive mechanical properties, and the product of strength and elongation is 43.5GPa·%.

Structural Styles and their Suitability for Hydrocarbon in Eastern Sindh Monocline, Lower Indus Basin, Pakistan

The present study is aimed to recognize the structural styles of hydrocarbon exploration and petrophysical properties of the LGF. The 2-D seismic and well log data set is composed of three seismic lines and well log data of Chak 66–1. Five horizons have been marked with the help of well to seismic tie namely tops of Ranikot, Parh, upper Goru, lower Goru, basal and top massive sands, and out of which basal and massive sands are the objective focus of the present study. Based on seismic data, the study area is characterized by normal faults showing NW–SE dipping trend. Horst and graben structural features are prominent on the seismic lines, which indicated the extensional tectonic regime. Time–depth contour maps and 3D surfaces of objective horizons depict their actual spatial distribution in this area. Wireline logging analysis revealed the physical properties of both basal and massive grains of sand, as 17% effective porosity, 25% average volume of shale (Vsh), 40% water and 60% hydrocarbon saturations for basal sands, Whereas, 16% effective porosity, 35% Vsh, 30% water and 70% hydrocarbon saturations are interpreted for massive sands. Cross–plots of Nphi–Dt and Dt–Rhob also identified that both areas of sand are clean, gas–saturated and have the potential to produce hydrocarbons.

Dynamics and head-on collisions of multidimensional dust acoustic shock waves in a self-gravitating magnetized electron-depleted dusty plasma

The dynamics and collisions of dust acoustic (DA) shock excitations traveling in opposite directions are theoretically investigated in a three-dimensional self-gravitating magnetized electron-depleted dusty plasma whose ingredients are extremely warm positively and negatively charged massive dust grains as well as ions that follow the q-nonextensive distribution. A linear analysis and the extended Poincare–Lighthill–Kuo method are used to derive the dispersion relation, the two-sided Korteweg–de Vries Burgers equations, and the phase shift that occurs due to the wave interaction. It is found that gravitation introduces Jeans-like instability, reduces the wave damping rate, decays the aperiodic oscillatory structure of DA excitations, and strongly affects the amplitude, steepness, and occurrence of monotonic compressive and rarefactive shocks. Numerical simulations also highlighted the stabilizing role of the magnetic field and the singularities of the collision process of monotonic shock fronts as well as the undeniable influence of viscosity, ion nonextensivity, and obliqueness between counter-traveling waves on the phase shift and collision profiles. The present results may be useful to better understand interactions of dust acoustic shock waves in the laboratory and astrophysical scenarios, such as dust clouds in the galactic disk, photo-association regions separating H II regions from dense molecular clouds, Saturn's planetary ring, and Halley Comet.

Effect of Yttrium on the Microstructure and Mechanical Properties of PH13-8Mo Stainless Steels Produced by Selective Laser Melting.

In the present work, PH13-8Mo stainless steel parts without yttrium and with yttrium (Y) were manufactured by selective laser melting (SLM). The microstructure, phase composition and grain orientation of the stainless steels parts with Y and without Y were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), electron-backscatter diffraction (EBSD), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). The characterization results revealed that the addition of Y clearly refined the grain size of the PH13-8Mo steel formed part, resulting in more equiaxed massive grains and in a less anisotropic microstructure. PH13-8Mo stainless steel formed parts were mainly composed of martensite and retained austenite. The addition of Y could significantly increase the content of retained austenite and also generate nano-sized precipitates containing Y. The mechanical test results showed that both strength and toughness of the shaped parts containing Y were improved synergistically. The yield strength reached 1443 MPa, the elongation was 12.2%, and the room temperature impact energy reached 124.25 J/cm2. The strengthening and toughening by Y of the formed parts were mainly attributed to grain refinement, higher volume fraction of the retained austenite and the formation of nano-sized precipitates containing Y.

Microstructure evolution and mechanical properties of a Fe, Cr-rich multiphase Ni3Al-based superalloy during transient liquid phase bonding process

In this paper, a Fe, Cr-rich multiphase Ni3Al-based alloy is joined through transient liquid phase bonding (TLP) technique. Different from typical γ+γ′ dual phase Ni3Al-based alloys, the joint can be divided into three distinct zones: isothermal solidification zone (ISZ), gamma prime zone (GPZ) and diffusion affected zone (DAZ). Interestingly, the massive fine grains with γ+γ′ dual phase are observed inside the ISZ, and the GPZ consists of blocky γ′ phase. The precipitation of Cr-rich borides in DAZ provides an advantageous compositional condition for the local coarsening of γ′ phase. In addition, hardness value of the bonded samples fluctuates from the centerline to the BM and reaches the peak at the DAZ. The bonded specimens share equivalent room-temperature tensile strength and elongation to failure with the parent metal after the weld thermal cycle. Moreover, the fracture path propagates along the base metal (BM), which indicates excellent tensile properties of the joint.

Electrostatic Shock Structures in a Magnetized Plasma Having Non-Thermal Particles

A rigorous theoretical investigation has been made on the nonlinear propagation of dust-ion-acoustic shock waves in a multi-component magnetized pair-ion plasma (PIP) having inertial warm positive and negative ions, inertialess non-thermal electrons and positrons, and static negatively charged massive dust grains. The Burgers’ equation is derived by employing the reductive perturbation method. The plasma model supports both positive and negative shock structures in the presence of static negatively charged massive dust grains. It is found that the steepness of both positive and negative shock profiles declines with the increase of ion kinematic viscosity without affecting the height, and the increment of negative (positive) ion mass in the PIP system declines (enhances) the amplitude of the shock profile. It is also observed that the increase in oblique angle raises the height of the positive shock profile, and the height of the positive shock wave increases with the number density of positron. The applications of the findings from the present investigation are briefly discussed.

Structural Styles and their Suitability for Hydrocarbon in Eastern Sindh Monocline, Lower Indus Basin, Pakistan

The present study is aimed to recognize the structural styles of hydrocarbon exploration and petrophysical properties of the LGF. The 2-D seismic and well log data set is composed of three seismic lines and well log data of Chak 66–1. Five horizons have been marked with the help of well to seismic tie namely tops of Ranikot, Parh, upper Goru, lower Goru, basal and top massive sands, and out of which basal and massive sands are the objective focus of the present study. Based on seismic data, the study area is characterized by normal faults showing NW–SE dipping trend. Horst and graben structural features are prominent on the seismic lines, which indicated the extensional tectonic regime. Time–depth contour maps and 3D surfaces of objective horizons depict their actual spatial distribution in this area. Wireline logging analysis revealed the physical properties of both basal and massive grains of sand, as 17% effective porosity, 25% average volume of shale (Vsh), 40% water and 60% hydrocarbon saturations for basal sands, Whereas, 16% effective porosity, 35% Vsh, 30% water and 70% hydrocarbon saturations are interpreted for massive sands. Cross–plots of Nphi–Dt and Dt–Rhob also identified that both areas of sand are clean, gas–saturated and have the potential to produce hydrocarbons.

Extraction of Al from Coarse Al-Si Alloy by The Selective Liquation Method.

A selective liquation process to extract Al from a coarse Al–Si alloy, produced by carbothermal reduction, was investigated on the laboratory scale. The products obtained by selective liquation–vacuum distillation were analyzed by X-ray diffraction, inductively coupled plasma optical emission spectrometry and scanning electron microscopy. During the selective liquation process with the use of zinc as the solvent, the pure aluminum in the coarse Al–Si alloy dissolved in the zinc melt to form an α-solid solution with zinc, and most of the silicon and iron-rich phases and Al–Si–Fe intermetallics precipitated and grew into massive grains that entered into the slag and separated with the Zn–Al alloy melt. However, some fine silicon particles remained in the Zn–Al alloy. Thus, Al–Si alloys conforming to industrial application standards were obtained when the Zn–Al alloys were separated by a distillation process.

Modulational instability of dust‐ion‐acoustic waves in pair‐ion plasma having non‐thermal non‐extensive electrons

AbstractThe modulational instability (MI) criteria of dust‐ion‐acoustic (DIA) waves (DIAWs) have been investigated in a four‐component pair‐ion plasma having inertial pair ions, inertialess non‐thermal non‐extensive electrons, and immobile negatively charged massive dust grains. A nonlinear Schrödinger equation (NLSE) is derived by using reductive perturbation method. The nonlinear and dispersive coefficients of the NLSE can predict the modulationally stable and unstable parametric regimes of DIAWs and associated first and second‐order DIA rogue waves (DIARWs). The MI growth rate and the configuration of the DIARWs are examined, and it is found that the MI growth rate increases (decreases) with increasing the number density of the negatively charged dust grains in the presence (absence) of the negative ions. It is also observed that the amplitude and width of the DIARWs increase (decrease) with the negative (positive) ion mass. The implications of the results to laboratory and space plasmas are briefly discussed.

Native copper formation associated with serpentinization in the Cheshmeh-Bid ophiolite massif (Southern Iran)

In the Cheshmeh-Bid district of the Khajeh-Jamali ophiolitic massifs (Southern Iran), mantle peridotites are intruded by abundant pyroxenite dykes. A few of these dykes are remarkable for the occurrence of native copper associated with the development of a metasomatic reaction zone. The dykes are progressively reacted, from their margins towards the center, with an amphibole + antigorite selvage, followed by a centimeter-thick clinopyroxene + antigorite assemblage and, finally, by the native copper-bearing zone consisting of clinopyroxene + chlorite + antigorite. Native Cu occurs along cleavages and partially healed fractures in clinopyroxene, and as massive grains intergrown with antigorite. Copper isotope signatures and thermodynamic calculations show that the main driver for reaction zone formation is Ca-metasomatism. Native copper forms at the expense of chalcocite in the reaction zone. Such a reaction can only occur in reducing conditions, in agreement with the analysis of fluid inclusions composition displaying H2 and CH4. Such fluids presumably originated from the hydration of mantle rocks. The observed reaction zone and native copper mineralization are thus interpreted as the result of Ca-metasomatism during hydrothermal alteration of the oceanic lithosphere. This is consistent with U/Pb dating of titanite, suggesting formation during the Albian when the dykes were exposed on the seafloor in a supra-subduction setting. The source for copper mineralization, as revealed by Cu isotopes, is probably mantle-like.

ION ACOUSTIC INSTABILITY IN DUSTY PLASMA

The computer simulation results of the ion acoustic instability evolution in the dusty plasma are presented. The dusty plasma consists from electrons, ions, massive charged dust grains and neutral atoms. In the simulation the implicit PIC-code is used. To this code the implicit scheme of particles movement is applied, namely the direct implicit method of Langdon-Fridman. Realization of the algorithm is presented too.

Dust-Acoustic Rogue Waves in Opposite Polarity Dusty Plasma Featuring Nonextensive Statistics

Modulational instability of dust-acoustic waves, which propagate in an opposite polarity dusty plasma system containing inertial warm negatively and positively charged massive dust grains as well as nonextensive q-distributed electrons and ions has been theoretically investigated. The nonlinear Schrodinger equation is derived by employing the reductive perturbation method. The nonlinear Schrodinger equation predicts the conditions of the modulational instability of dust-acoustic waves and the formation of dust-acoustic rogue waves in a nonlinear and dispersive plasma medium. It is observed that the basic features of the dust-acoustic rogue waves (viz., amplitude and width) are significantly modified by the various plasma parameters such as nonextensivity of electrons and ions, electron number density, electron temperature, ion number density, ion temperature, the mass and number density of the dust grains, etc. The application of the results in space and laboratory opposite polarity dusty plasma is briefly discussed.