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In the present exploration, it was attempted to understand the creep‐fatigue (CF) deformation micromechanisms of alloy CM 247 DS LC by conducting low‐cycle fatigue (LCF) and CF tests employing strain amplitude ranging from 0.6% to 1.0% at T = 850°C in the air and performing extensive electron microscopic examinations. The cyclic life of the alloy lessens for all CF tests conducted at 1 and 5 minute dwell time in comparison to LCF tests. Transmission electron microscopy (TEM) examinations confirmed that during CF tests substructure consists of dislocation loop, mixed dislocations, and γ' rafting, a typical creep deformation signature of nickel‐base superalloys, it also consists of features observed during fatigue deformation such as anti‐phase boundary (APB)‐coupled dislocations inside γ' precipitates and local tangles of dislocations. This confirms that the deformation of CF‐tested specimens is ascribed to the synergistic effect of both creep and fatigue. This fact was further verified by scanning electron microscopic (SEM) examinations. [ABSTRACT FROM AUTHOR]

Abstract: A multiscale modelling framework has been proposed to characterize microstructure evolution during hot strip rolling of transformation-induced plasticity (TRIP) steel. The modelling methodology encompasses a continuum dislocation density evolution model coupled with a lumped parameter heat transfer model which has been seamlessly integrated with a mesoscale Monte Carlo (MC) simulation technique. The dislocation density model computes the evolution of dislocation density and subsequently constitutive flow stress behaviour has been predicted and successfully validated with the published data. A lumped-parameter transient heat transfer model has been developed to calculate the average strip temperature in the time domain. The heat transfer model incorporates the effect of plastic work for different strain rates in the energy conservation formulation. A coupled initial value problem solver has been developed to integrate the system of stiff ordinary differential equations in the time domain to predict dislocation density and temperature profiles simultaneously. The temporal evolution of microstructure during hot rolling of TRIP steel is simulated by the MC method incorporating thermal and dislocation density data from the continuum models. Simulated microstructural maps, kinetics of recrystallization and grain size evolution have been generated in a 200×200 lattice system at different strain rates and temperatures. The simulation code has been implemented in a high-performance grid computing network. The predicted temporal evolution of grain size, recrystallized fractions and flow stress have been validated with the published literature and found to be in good agreement, confirming the predictive capability of the integrated model. [Copyright &y& Elsevier]

Abstract: The solution treated commercial grade AISI 304L austenitic stainless steel plate was heavily cold rolled to 90% of thickness reduction. Cold rolled specimens were annealed at various temperatures by thermal cycles and isothermal annealing. Strain-induced phase transformations and microstructure studies were carried out both in the cold rolled and annealed conditions. The X-ray diffraction and magnetic measurements were used for phase transformation studies. The transmission electron microscope characterisation revealed that the cyclic thermal process resulted in ultrafine grain austenite formation whereas, the isothermal annealing developed coarser grain size microstructure. The different microstructural evolutions by the above two processes largely influenced the development of the recrystallisation texture. The thermal cycling produced a distinct γ-fibre texture while the isothermal annealing resulted in a cube texture component along with the γ-fibre. The γ-fibre texture evolution was attributed to the over critical subgrains or nuclei and {100} 〈001〉 cube texture to the coarser grains of micrometer size. [Copyright &y& Elsevier]

A model to compute an effective microstructural length scale by fractal analysis of self-affine tensile fractographic images has been proposed. Good correlation between the characteristic microstructural length scale and the average circular diameter of voids as well as yield strength is demonstrated for a Cu-strengthened HSLA steel. Using the fractal-based model, fracture toughness is computed, which agrees well with that determined experimentally. [Copyright &y& Elsevier]

Abstract: In this study, addition of Ag micro-particles with a content in the range between 0 and 4wt.% to a Sn–Zn eutectic solder, were examined in order to understand the effect of Ag additions on the microstructural and mechanical properties as well as the thermal behavior of the composite solder formed. The shear strengths and the interfacial reactions of Sn–Zn micro-composite eutectic solders with Au/Ni/Cu ball grid array (BGA) pad metallizations were systematically investigated. Three distinct intermetallic compound (IMC) layers were formed at the solder interface of the Au/electrolytic Ni/Cu bond pads with the Sn–Zn composite alloys. The more Ag particles that were added to the Sn–Zn solder, the more Ag–Zn compound formed to thicken the uppermost IMC layer. The dissolved Ag–Zn IMCs formed in the bulk solder redeposited over the initially formed interfacial Au–Zn IMC layer, which prevented the whole IMC layer lifting-off from the pad surface. Cross-sectional studies of the interfaces were also conducted to correlate with the fracture surfaces. [Copyright &y& Elsevier]

Abstract: In the present study, a separate addition of the same amount of Al and Cu are added with the Sn–9Zn eutectic solder alloy to investigate the effect of a third element addition on the microstructural and mechanical properties as well as thermal behavior of the newly developed ternary solder alloys. The results indicate that both Al and Cu refine the microstructure and form intermetallic compounds with the eutectic solder alloy. The microstructures of the newly developed ternary Sn–9Zn–X solder alloys were composed of fine needle-like α-Zn phase with some IMC dispersed in the β-Sn matrix. The relatively small and compact shaped Al6Zn3Sn IMC was found to be uniformly distributed in the β-Sn phase which results in an increase in the tensile strength, due to the second phase dispersed strengthening mechanism. On the contrary, the large flower shaped Cu6Sn5 and rod shaped Cu5Zn8 IMC develops some sort of weak interface with the parent β-Sn matrix results in a decrease in the tensile strength. The microhardness of the Sn–9Zn–0.5Al ternary solder alloys was also higher than that of the Sn–9Zn–0.5Cu alloy. [Copyright &y& Elsevier]

Abstract: The variations in the FCGR curve, the J–R curve, the blunting-line slope and the stretch zone width (SZW) for systematic variation of microstructure in Cu-strengthened HSLA-100 steel has been studied. The microstructural variation in the steel has been introduced through ageing at various temperatures after an initial quenching treatment. This has resulted in progressive tempering of the as-quenched martensitic matrix, accompanied by nanoscale precipitation of coherent Cu particles that gradually coarsen and loose coherency with overageing. It was observed that although there was a systematic trend, the FCGR curves were least sensitive to microstructural changes. The variation of fracture toughness, characterized by J Q in most cases and by K Q for the microstructures displaying highest strengths, correlated well with the inverse relationship between fracture toughness and strength. A systematic trend was also observed for the pre-exponent and exponent of the power-law tearing curve (for cases in which brittle fracture was precluded), the blunting-line slope and the SZW. The effect of coherency of precipitates in restricting plastic flow, as implied from the variation of mechanical properties with ageing temperature is thought to be responsible for the effects observed. [Copyright &y& Elsevier]

The present paper reports the formation of novel morphologies of intermetallic compounds during the solidification of different Al–Fe–V–Si alloys using cooling rates ranging from 1 to 20 K s−1. The influence of cooling rate, composition of the alloy and the addition of Mg and Ni–20%Mg alloy on the morphology of the intermetallic phases, particularly that of Al13Fe4 phase, is reported. Al13Fe4 forms with a ten-armed star shaped morphology with small amount of Si (<1 wt.%) at a cooling rate of &ap;14 K s−1. A lower cooling rate and higher Si content result in degeneration of the ten-armed stars into other morphologies. The higher the Si content, the higher the cooling rate required to form the ten-armed star-shaped Al13Fe4 phase. Ten-fold growth morphology of the precipitates is formed due to twinning along (2 0 1¯) or (1 0 0) planes. The morphology, size and distribution of those precipitates can be considerably modified by Mg treatment. Treatment of an Al–8.3Fe–0.8V–0.9Si alloy melt with 1.5 wt.% of Mg or 1 wt.% of a Ni–20Mg alloy alters the ten-armed growth morphology to rectangular, hexagonal or other compact forms. [Copyright &y& Elsevier]

The grain refining response of aluminium (Al) was studied with as cast, rolled and heat-treated Al–5Ti master alloys. The Al–5Ti master alloy was prepared by the reaction of K2TiF6 with molten Al. The results showed that rolled master alloys exhibited better grain refining performance as compared to as cast master alloys. Similarly, heat-treated Al–5Ti master alloys showed improvement in the grain refining performance. The improvement in grain refining efficiency of master alloy on rolling has been attributed to the increased fraction of fine TiAl3 particles due to their fracture during rolling. The mean particle size of TiAl3 decreased with increase in the reduction level of rolling. The results also indicated that the morphology of TiAl3 particles changes from plate like in the as cast condition to blocky type after rolling due to fracture of plate like particles. The improved grain refining efficiency of the master alloy on heat treatment was attributed to the increased volume fraction of TiAl3. [Copyright &y& Elsevier]

Mullite aggregates were synthesised from beach sand sillimanite, a by-product generated during rare earth extraction, by reaction sintering with calcined alumina. The aggregates were characterised in terms of chemical composition, mineral phases, microstructure and important thermo-mechanical properties critical for refractory applications. To evaluate its suitability in castable refractories, low cement castables were prepared using the aggregates with commercial high alumina cement. The physical and thermo-mechanical properties such as bulk density, apparent porosity, cold crushing strength, hot modulus of rupture and compressive creep was studied in relation to temperature. The castables exhibited good modulus of rupture and excellent creep resistance at 1400 °C. Attempts were made to correlate these properties with corresponding microstructure and phases. [Copyright &y& Elsevier]

Fabrication of β-SiC mats using natural fibers was investigated by incorporating tetraethyl orthosilicate (TEOS) into the micro-tunnels of the Jute fibers and pyrolysing them at elevated temperatures. The silicon compound (TEOS) impregnated Jute mats were hydrolyzed by adding HCl or ammonia solution at room temperature and subsequently, the mats containing silicon hydroxide were pyrolysed in inert argon atmosphere at high temperatures to yield the β-SiC mats. The fabricated mats are expected to be used for high temperature blankets and for making of laminated metal matrix composites and functionally gradient materials (FGMs). [Copyright &y& Elsevier]

Abstract: We have observed good ferroelectric loops at room temperature in hexagonal HoMnO3 (HMO) bulk ceramics sintered at 1250°C. Microstructure and ferroelectric hysteresis loops are observed to be dependent on sintering temperature. It is observed that with an increase of sintering temperature, hexagonal a-axis is compressed and c-axis is marginally dilated with overall contraction of the hexagonal unit-cell volume. We explain the origin of ferroelectricity through relative movement of Ho ion and Mn ion within its unit-cell volume, resulting in the distortion of unit-cell volume. We argue that ferroelectric origin of hexagonal HMO at room temperature may be due to the marginal displacement of Ho ion along a-axis, that influences the exchange interaction among the Mn3+ and Ho3+ ions, causing magnetically induced ferroelectricity at room temperature. [Copyright &y& Elsevier]

Abstract: Magnesite-chrome aggregates have been prepared from friable chrome ore and magnesia of different reactivity in the presence of an additive, ZrO2. Two types of batch compositions using sintered magnesia, caustic magnesia and chrome ore have been selected for preparing mag-chrome composites. The batch consisting of sintered magnesia and friable chrome ore (SMC) was vibromilled for 8h, whereas caustic magnesia compositions were added directly to a vibromilled chrome ore (CMC) and mixed in a fluidized bed mixer. Additions of 1–5wt.% ZrO2 were made to the batches. Firings were carried out between 1700 and 1750°C with 2h soaking. Aggregates were characterized by evaluating densification, hot modulus of rupture and microstructure. The reactivity of magnesia was found to play an important role in the final properties of samples. Introducing less reactive sintered magnesia improved all the properties of the aggregates. ZrO2 was found to be a good sintering aid in the magnesite-chrome composites. [Copyright &y& Elsevier]

Magnesite–chrome composites have been prepared by utilizing sintered magnesite and friable chrome ore in presence of titania as additive. Three types of batch compositions containing 5% Cr2O3, 18% Cr2O3 and 30% Cr2O3 have been selected for developing mag–chrome composites. The aggregates were developed by first vibro milling the raw materials and then additives were incorporated in wt.% along with 5% PVA solution as binder to the different batches. It was then properly mixed by fluidized bed mixer and after sieving in 20-mesh BS sieve briquettes were formed uniaxially at a pressure of 100 MPa. The briquettes were first air dried and subsequently oven dried at 110±5 °C for 24 h. Finally, the green briquettes were fired at 1700 and 1750 °C in electrically program controlled muffle furnace. The physical properties as well as thermo-mechanical properties and microstructural studies of the sintered aggregates have been evaluated. The common feature observed in the microstructures is the exsolution of spinel phase in magnesia grains. The hot properties of the composites are superior when the Cr2O3 content is increased to 30%. Additives played a significant role in improving the bulk density and strength. [Copyright &y& Elsevier]

Abstract: Mechanically activated granulated blast furnace slag (GBFS) was used in the range of 50–95% to replace clinker in portland slag cement (PSC). The slag and clinker were activated separately using an attrition mill and mixed to prepare cement formulations. Use of activated slag resulted in a remarkable increase in strength vis-à-vis commercial slag cement. Both 1-day and 28-day strength were found to increase with an increase in slag content up to 70%. The strength of the sample containing 80–85% slag was comparable to the commercial cement used as a reference. It was observed that mechanical activation of slag was more critical from the point of view of strength development. The hydrated cement samples were characterised using powder X-ray diffraction (XRD), scanning electron microscopy with X-ray microanalysis (SEM-EDS) and simultaneous thermogravimetry and differential thermal analysis (TG/DTA). It is established that microstructural changes resulting from enhanced reactivity of slag and densification are related with the improvement in cement strength. [Copyright &y& Elsevier]

Abstract: The failure of a high mast lamp post was analysed. The mast failed by bending at a position just opposite to the maintenance pocket. It appears that the failure was due to wind load, which the structure could not bear. The elemental analysis and mechanical properties determination of the failed mast materials was as per the recommended values. However, the mechanical properties were slightly higher compare to recommended values and this is because of the presence of very fine pearlite in the microstructure. The probable causes might be due to faulty installation and/or damage during installation, severe weather condition or events such as high-speed storm, etc. or fatigue caused by the unpredictable phenomenon of harmonic vibration. [Copyright &y& Elsevier]

Magnesium aluminate spinel was synthesized by solid oxide reaction route at 1400 °C and then added to magnesia refractory brick compositions in the range of 0–30 weight percentages. Optimum firing temperature of the magnesia–spinel refractory composites was determined from densification study and phase analysis. Final refractory products were then characterized by thermal expansion, refractoriness under load, cold strength, retainment of cold strength after thermal shock, hot strength at different temperatures and micro-structural analysis. Spinel (20 wt.%) containing magnesia composition was found to have superior properties. [Copyright &y& Elsevier]

Stoichiometric magnesium aluminate spinel was synthesized by reaction sintering of alumina with caustic and sintered magnesia. The volume expansion of 5–7% during MgAl2O4 formation was utilized to identify the starting temperature of spinel formation and densification by high temperature dilatometry. The magnesia reactivity was determined by measurement of crystallite size and specific surface area. Caustic magnesia and sintered magnesia behave differently vis-a&grave;-vis phase formation and densification of spinel. Densification of stoichiometric Mag-Al spinel was carried out between 1650 and 1750 °C. Attempts were made to correlate the MgO reactivity with microstructure and densification of spinel. [Copyright &y& Elsevier]

Densification of two different nonstoichiometric spinels (Al2O3 content 66 wt.% and 90 wt.%) was studied by using the reaction sintering technique. Sintered sea water magnesia and commercial alumina were used as starting materials. Reactivity of alumina was changed by calcinations between 800 and 1600 °C. Sintering for all the batches was carried out in the temperature range of 1600 and 1700 °C. Sintered products were characterized by bulk density, phase analysis and microstructure. Alumina calcined at 1200 °C was found to be optimum for densification of non-stoichiometric spinels. [Copyright &y& Elsevier]