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[Display omitted] • The exceptional hardness of Ti-based materials, 40% plus above the hardness of the base alloy, was achieved without compromise to low specific weight of the material. • The addition of TiC to the alloy Ti-6Al-4 V in an amount of 40% leads to the formation of a discontinuous composite and an increase in the hardness of the material; with a higher particle content, the composite becomes continuous, exhibiting very fragile behavior. • TiC chemically reacts with the matrix alloy and forms a strong interfacial bond with the base alloy. • As a result of high temperature aging of the composite, the hard phases of Ti 2 C and Ti 3 AlC formed in the expense of a relatively soft matrix alloy and further contribute to a significant increase in hardness. Titanium alloy composites, reinforced with a light second phase and made using inexpensive powder metallurgy, attract considerable attention due to the directness of their intentional hardness increase without compromising low weight of materials. In this study the metal-matrix composites (MMC) of Ti-6Al-4V alloy reinforced with light and hard particles of TiC (up to 80%, vol.) were made using blended elemental powder metallurgy of hydrogenated titanium. Post-sintering solution treatment for 45 min. at 880 °C and 1000 °C and water quenching followed by the 5 hrs. aging at 550 °C was used to additionally refine the microstructure and properties of MMC. For the duration of thermal exposure throughout solution treatment and additional aging the matrix and reinforcement phase underwent distinct structural changes that modified the mechanical properties of materials. It has been shown that the used reinforcement presents an exceptional opportunity for hardening of Ti-based composites without compromising their low specific weigh. It can increase the hardness of material by more than 40% due to the ability of TiC to chemically react with the matrix to form a strong interfacial bond and its ability to form hard compounds of Ti 2 C and Ti 3 AlC in the expense of the relatively soft matrix alloy. [ABSTRACT FROM AUTHOR]

In this study, a novel friction-based welding technology was proposed for fabricating Al/Cu bimetallic tubes. The frictional heat and radial pressure during the friction-based welding process are used to achieve the metallurgical bonding between Al and Cu tubes in a rapid and efficient way. Successful joints indicate that this technology has the potential for fabricating bimetallic tubes. Microstructure evolution, bonding mechanism and mechanical properties of Al/Cu bimetallic tubes were also analyzed. Results reveal that columnar α-Al, intermediate transition layer and intermetallic compounds (IMC) are identified at the rotational speed of 950 rpm. While the rotational speed is decreased to 95 rpm, only solid-state diffusion occurs at the interface which results in three IMC layers, Al 2 Cu, AlCu, and Al 2 Cu 3 . The thickness of the Al 2 Cu is more significantly affected by the rotational speed than that of AlCu and Al 2 Cu 3 . Maximum hardness is observed at the reaction layer due to the formation of IMC. The appearance of intermediate transition and thick Al 2 Cu layer weakens the bonding strength of bimetallic tubes. The joints are fractured at the reaction layers, and the fracture exhibits typical brittle characteristic. Three crack propagation paths are observed at the interface of Al/Cu bimetallic tubes. [ABSTRACT FROM AUTHOR]

In order to explore a novel material for thermal barrier coatings (TBCs), the composite ceramic materials of lanthanum zirconate (La 2 Zr 2 O 7 ) and lanthanum phosphate (LaPO 4 ) were prepared by calcining. The phases and micro-structures of La 2 Zr 2 O 7 /LaPO 4 composite ceramic materials were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The properties of La 2 Zr 2 O 7 /LaPO 4 material, such as thermal conductivity, coefficient of thermal expansion (CTE) and mechanical properties of La 2 Zr 2 O 7 /LaPO 4 were investigated using laser flash method, high-temperature dilatometer and micro-hardness test. Based on XRD patterns, the pyrochlore and monazite phases were obtained in La 2 Zr 2 O 7 /LaPO 4 composite ceramic material without any chemical reaction. According to SEM morphology, the La 2 Zr 2 O 7 was closely near to LaPO 4 along with a lot of pores, it might cause the decrease of thermal conductivity. The thermal conductivities of composite ceramics were similar to that of La 2 Zr 2 O 7 . The CTE of them were about 10 × 10 − 6 K − 1 , which was close to the value of LaPO 4 . Because of doping LaPO 4 , hardness and Young's modulus of samples were lower than that of La 2 Zr 2 O 7 . The studies revealed that the La 2 Zr 2 O 7 /LaPO 4 composite ceramics had good mechanical and thermal physical properties and could be applied as new candidate materials for TBCs in the future. [ABSTRACT FROM AUTHOR]

Multilayer architecture based on CrAlN coatings to improve their properties attracts great attention. Here, the structure, mechanical and thermal properties of CrAlN/ZrN multilayer coatings with bilayer periods of ~ 5 and 9 nm are investigated. Decreasing bilayer period of CrAlN/ZrN coating from 9 to 5 nm results in a transformation of interfacial structure between CrAlN and ZrN sublayers from nonepitaxial to local epitaxial interfaces, and thereby has a positive effect on the hardness, adhesion strength, thermal stability and oxidation resistance. Additionally, a layer by layer oxidation behavior of CrAlN/ZrN coatings leads to the formation of lamellar oxide scale. [ABSTRACT FROM AUTHOR]

In this paper hybrid welding of the annealed AA5754 alloy was studied and the role of post weld heat treatment (PWHT) on microstructure and mechanical properties was investigated. The microstructure and hardness of the base material and welds were analyzed. Due to the segregation, the lowest microhardness value was observed at the welding centerline. High microhardness was registered in a narrow zone at the interface between the fusion zone and the heat affected zone where the welding cycle promotes both the strengthening by Mg solid solution and the lowest grain size. The hardness of the heat affected zone was higher than that of the base material due to dissolution of soluble particles (Mg 2 Si and Mg 2 Al 3 ). PWHT at 350 °C increased the microhardness in the fusion zone and the tensile strength with respect to the untreated joint, whereas the strain at fracture was similar showing that the fracture was promoted mainly by the presence of porosity, coarse grain size and insoluble segregated second phases. [ABSTRACT FROM AUTHOR]

Nanostructuring has been considered an effective approach to enhance the thermoelectric (TE) performance of materials by reducing their lattice thermal conductivity. In the present study, we show the influence of a process control agent (PCA) for ball milling, Stearic acid (SA), on the nano- and microstructure and thermoelectric properties of type-I clathrates in the Ba-Cu-Si system, which are promising candidates for TE applications. The SA effectively reduces cold welding and prevents particle agglomeration during ball milling. Consequently, it increases the powder yield and the milling efficiency. Smaller grain/crystallite sizes are obtained in the as-milled powders than without SA. Importantly, the SA forms nano-layers around the clathrate particles, which inhibit the grain growth during the hot pressing process used for powder compaction. Therefore, smaller grain sizes are also obtained in the hot-pressed samples. They show increased hardness and reduced thermal conductivity but also increased electrical resistivity. However, as the phonon transport is more strongly degraded than the charge transport, we observe 15% enhancement in the dimensionless thermoelectric figure of merit ZT by adding the PCA. [ABSTRACT FROM AUTHOR]

SiGe based thermoelectric (TE) materials have been employed for the past four decades for power generation in radio-isotope thermoelectric generators (RTG). Recently "nanostructuring" has resulted in significantly increasing the figure-of-merit (ZT) of both n and p-type of SiGe and thus nanostructured Si80Ge20 alloys are evolving as a potential replacement for their conventional bulk counterparts in designing efficient RTGs. However, apart from ZT, their mechanical properties are equally important for the long term reliability of their TE modules. Thus, we report the mechanical properties of p-type nanostructured Si80Ge20 alloys, which were synthesized employing spark plasma sintering of mechanically alloyed nanopowders of its constituent elements with 1.2% boron doping. Nanostructured p-type Si80Ge20 alloys exhibited a hardness of ~ 9 ± 0.1 GPa, an elastic modulus of ~ 135 ± 1.9 GPa, a compressive strength of 108 ± 0.2 MPa, and fracture toughness of ~ 1.66 ± 0.04 MPavm with a thermal shock resistance value of 391 ± 21 Wm-1. This combination of good mechanical properties coupled with higher reported ZT of nanostructured p-type Si80Ge20 alloys are rendered to be a potential material for power generation applications, compared to its bulk counterpart. [ABSTRACT FROM AUTHOR]

TiO2 and (NdyTi1-y)Ox thin films were deposited by reactive magnetron sputtering process from mosaic Ti-Nd targets and characterised by X-ray diffraction (XRD), Raman optical spectroscopy and nanoindentation technique. XRD measurements revealed that as-prepared titanium dioxide and TiO2 thin films with 4 and 7 at.% of Nd had nanocrystalline rutile structure, while coatings with larger amount of Nd were amorphous. Raman spectroscopy investigations showed that the increase of the neodymium concentration caused amorphisation of the coatings and hindered their crystal growth. All as-prepared coatings were transparent in the visible wavelength rangewith a transmittance of approximately 80%. The refractive index and extinction coefficient of the thin films gradually decreased with the increase of the neodymium concentration. Micro-mechanical properties, i.e. hardness and elasticmodulus, were determined using traditional load-controlled nanoindentation testing and continuous stiffnessmeasurements. The highest hardness and elastic modulus valueswere obtained for thin filmswith 7 at.% of Nd and were approximately 14.8 GPa and 166.3 GPa, respectively. [ABSTRACT FROM AUTHOR]

The influence of individual manufacturing steps during industrial wire drawing processes on the mechanical and corrosion properties of the 6056 aluminum alloy was investigated. These steps demonstrated an essential influence on the microstructure, and thus, the susceptibility to intergranular corrosion (IGC). No clear correlation between IGC susceptibility and hardness was observed. Although the highest resistance against intergranular attack was determined for those alloys in the solution annealed condition, pitting corrosion was identified to occur. Subsequent artificial aging of the solution annealed and quenched wires reintroduced IGC susceptibility; this phenomenon was attributed to the occurrence of galvanic coupling between the noble Cu-phases, located on the grain boundary, and the anodic grain boundary area. [ABSTRACT FROM AUTHOR]

Highlights: [•] The study sheds new light on the natural aging of AA7136 friction stir welds. [•] Natural aging notably influences the mechanical properties of friction stir welds. [•] The hardness profile can be correlated to the temperature distribution model. [•] The GP(I) zones formation is responsible for the increased mechanical properties. [•] Natural aging cannot be neglected in practical applications of the FSW process. [ABSTRACT FROM AUTHOR]

Highlights: [•] Development of polymer/clay nanocomposites. [•] Compatibility of ABS and montmorillonite nanoclay and composition capability of them. [•] Effect of nanoclay content and process parameters on the mechanical properties of nanocomposite. [•] Analyzing the distribution of nanoclay layers using XRD test. [•] Dependency of tensile strength and hardness to the nanoclay content and processing conditions. [Copyright &y& Elsevier]

Abstract: Polypropylene (PP) is one of the most common thermoplastic materials in the world. There is a need to recycle the large amount of this used material. To overcome the environmental problems, related to the polymer waste, PP was recycled and used as a matrix material in different composites that can be used in high value applications. In this paper, composites made of recycled polypropylene (RPP) reinforced by glass fibres and/or wood flour of the palm tree were prepared, characterized and modeled. The mechanical and thermal properties of these recycled polymer matrix composites (RPMCs) were measured experimentally and modeled theoretically. The mechanical properties included tensile modulus, tensile strength and hardness, whereas thermal properties included thermal stability, melting and crystallinity percentage content were studied. In addition we applied the functionally graded materials concept, the elastic finite element analysis of a layered functionally graded pressurized pipe, which is one of the practical industrial applications, was accomplished in order to have some insight on the performance of such RPMCs. The results reveal that the desired mechanical and thermal properties met the requirements of a wide range of practical applications which can be attained by adding the considered fillers. Also, the proper selection of the layers of the pressurized pipe, which was made of RPMCs, led to decrease of the induced stresses and accordingly increased the operational safety. [Copyright &y& Elsevier]

Highlights: [•] Hardness is independent of general stresses at dominating plasticity. [•] Elastic deformations introduce a stress dependence of hardness. [•] Equi-biaxial tensile stresses increase stress dependence. [ABSTRACT FROM AUTHOR]

Highlights: [•] Effect of welding velocity and pulse frequency in GMAW of HSLA steel. [•] Dependency of weldment microstructure on the welding velocity and pulse. [•] Reduction of hardness in the weld zone and HAZ with increasing of heat input. [•] The higher strength due to the higher amount of martensite. [•] Deterioration of impact properties with formation of grain boundary ferrite. [ABSTRACT FROM AUTHOR]

Highlights: [•] Production of MMC reinforced with in situ boride particles have been investigated. [•] Higher reinforcement percentage of borides was produced by a filtration technique. [•] Hardness of boride particles was measured as approximately 3050Hv. [•] The cumulative weight loss of the composite was lower than of the matrix alone. [ABSTRACT FROM AUTHOR]

Abstract: In the paper, the effects of processing parameters (rotational speed and duration time) on microstructure, mechanical properties of 6061-T4 aluminum alloy friction stir spot welds were investigated. Experimental results indicate that the microstructure and mechanical properties varied significantly depending on processing parameters, which significantly affect the hook geometry and material flow which in turn affected the size of stir zone. The hardness profile of the weld exhibited a W-shaped or an upside down V-shaped appearance and the minimum hardness was obtained in the periphery of the thermo-mechanically affected zone (TMAZ) and heat affected zone (HAZ). The tensile/shear strength increased with increasing tool rotational speed and duration time, in which, the rotational speed played a crucial role in determining the strength. The cross-tension strength increased dramatically with increasing duration time at the highest rotational speed. There was a direct correlation between the effective weld width and the strength, the presence of larger effective weld width resulted in stronger weld. Two failure modes were observed: shear fracture of the nugget under tensile/shear loading, and nugget debonding under cross-tension loading, the fracture path was associated to the hook geometry. [Copyright &y& Elsevier]

Abstract: The gradient mechanical properties were obtained in the electropulsing-tempered saw blade made by the high carbon steel. The tooth has a high hardness, whereas at the back the hardness is low. Owing to the high temperature induced by the electropulsing, a plastic area formed at the tooth root. In addition, the thermal compressive stress and the strong electroplasticity effect at the tooth root helped heal the cracks there effectively. Therefore, the strength and toughness of the saw blade were improved obviously, making it meet the high requirements for the cutting performance. The results are attributed to the detour effect of the pulse current during the electropulsing–tempering treatment. [Copyright &y& Elsevier]

Abstract: Reverse dual-rotation friction stir welding (RDR-FSW) has great potential to obtain appropriate welding conditions through adjusting the independently rotating tool pin and surrounding shoulder. The welding torque exerted on the workpiece by the reversely rotating shoulder also cancels off a part of the welding torque exerted by the rotating tool pin, thus the clamping requirement for the workpiece is also reduced. In the present paper, a tool system for the RDR-FSW was designed and successfully applied to weld high strength aluminum alloy 2219-T6, and then microstructures and mechanical properties of the optimized joint were investigated to demonstrate the RDR-FSW characteristics. The weld nugget zone was characterized by the homogeneity of refined grain structures, but there was a three-phase confluction on the advancing side formed by different grain structures from three different zones. The tensile strength of the optimized joint was 328MPa (73.7% of the base material), showing an obvious improvement when compared with the optimized joint welded by the FSW without the reversely rotating assisted shoulder. The tensile fracture occurred in the ductile fracture mode and the fracture path propagated in the weakest region where the Vickers hardness is the minimum. [Copyright &y& Elsevier]

Abstract: The correlation of hardness values at scratch testing is studied within the framework of a differentiated description of representative stress values. The analysis is based on hardness values determined from a comprehensive finite element study of scratching of classical elastoplastic materials using a conical indenter. Large deformations are accounted for and the strain-hardening behaviour is varied in order to achieve generality of results. It is shown that good accuracy predictions for different material classes can be achieved by using a combination of stresses at different levels of plastic strains to define representative quantities at scratching. It is also shown that this correlation must account for the difference in mechanical behaviour at elastoplastic and rigid plastic scratching. From a practical point of view the results are valuable both when describing the mechanical behaviour at scratching and at material characterization. From the generality of the analysis, both elastoplastic and rigid plastic behaviour are accounted for, predictions based on the present study can be made for scratching of highly elastic materials such as polymers and ceramics but also for scratching of metals when plasticity dominates. [Copyright &y& Elsevier]

Abstract: The aim of this study was to determine the effect of the maleic anhydride grafted polypropylene (PP-g-MAH) on the properties of short carbon fiber (CF) reinforced polypropylene (PP) composites. The composites were prepared by melt blending and injection molding techniques at different percentages of CF. Tensile tests, hardness, differential scanning calorimeter (DSC) and scanning electron microscopy (SEM) were performed to characterize the physical and morphological properties of the prepared composites. It was observed from SEM photographs that modification with PP-g-MAH improved the interfacial adhesion between the carbon fibers and PP matrix. The ultimate tensile strength, hardness and modulus values of modified PP composites were higher compared to the values of CF reinforced PP composites. Melting temperature of all composites was not changed significantly with increasing CF content; however degree of crystallinity values were decreased with the increasing CF content level. [Copyright &y& Elsevier]

Abstract: A study has been conducted to investigate the mechanical and wear behaviors of the Al–12Si–XMg alloys (where Mg contents were 5%, 10% and 20%) cast by adding modifiers such as Sr, red phosphorous and salt mixtures. Mechanical properties were determined by hardness measurements, compression and wear tests. Reciprocating wear tests were conducted by rubbing ceramic (Al2O3) and steel (AISI 52100) balls on the unlubricated surfaces by applying the normal load of 2N. The microstructure of the Al–12Si–XMg alloys consisted of the Si needles and Mg2Si precipitates (two morphologies of which are polyhedral shape dark particles and grey colored components of Chinese script) in the Al matrix. Results demonstrated that volume fraction and size of the primary Mg2Si particles increased with increasing the Mg content. Mg containing alloys exhibited higher hardness and better wear resistance than the Mg free alloy. [Copyright &y& Elsevier]

Abstract: One of the main problems in the design of complex Al–Si cast components is the wide variety of mechanical properties in different regions of the castings which is due to the wide range of solidification microstructures, related to the local solidification conditions. There are many papers available on the widely used A356/A357 Al–Si–Mg alloys, however, most experimental data on their tensile or fatigue properties are generally obtained from specimens cast separately or produced under controlled laboratory conditions, that are extremely different from those of industrially cast components. Moreover, most of these data often relate the mechanical properties to only one microstructural parameter, such as solidification defects or secondary dendrite arm spacing, and do not take their simultaneous effect into consideration. For all these reasons, the main problem, in the design phase, is the lack of knowledge of the true local mechanical properties in complex-shaped castings, which often means a conservative approach is necessary, with a consequent increase in thickness and therefore in weight. The aim of this research was to study a complex A356 gravity die cast cylinder head, in order to verify the range of variability of the main microstructural parameters and tensile properties, using specimens directly machined from the casting. The component was heat treated at the T6 condition, and the effect of the delay between quenching and aging on the alloy hardness was also evaluated. Simple experimental equations have been proposed, able to successfully predict the local tensile properties in the casting, when only the most important microstructural parameters and alloy hardness are known. These equations allow the designer to predict the local tensile behaviour without any tensile tests; moreover they can also link the post-processing results of the casting simulation software to the pre-processing phase of the structural ones, with an approach of co-engineered design. [Copyright &y& Elsevier]

Abstract: The thixoextrusion process is a new method for manufacturing complicated and net shape components through which high strength materials can be formed more easily. In this study 7075 Al alloy which has low extrudability has been thixoformed by forward extrusion process. As it is known conventional extrusion of 7075 Al alloy has been very difficult due to high strength and multi-phase microstructural characterization. In this research, by applying the advantages of semisolid processing, the applied pressure for extrusion is decreased and desired mechanical properties were reached near the standard predictable properties for wrought 7075 Al alloy under T6 tempering conditions, for example tensile and yield strength and hardness of samples of thixoextrusion product sufficiently agree with same expected properties of wrought 7075 Al alloy and only elongation is decreased along this process. [Copyright &y& Elsevier]

Abstract: This paper describes wear behavior of powder metallurgy (PM) 316L stainless steel with additions of elemental boron with the aim of producing superior mechanical properties. The wear test of the samples is conducted using a pin specimen of PM 316L stainless steel doped with elemental boron and a steel disc specimen with hardness of 180 HV10. Densification achieved with boron addition due to the liquid phase formation up to 95% of theoretical density with 0.6wt.% boron addition. Most mechanical properties such as hardness, tensile strength and yield strength were improved with boron addition. The wear rate of PM 316L stainless steel decreased from 4.3×10−6 to 0.8×10−6 mm3/Nm with the addition of 0.6wt.% elemental boron. The abrasive-induced delamination wear dominated at the samples. Scanning electron microscopy observations of the worn surfaces revealed that plastic deformation occurred with delamination of surface layers in the sintered conditions. [Copyright &y& Elsevier]

Abstract: Failure behavior of low carbon steel resistance spot welds in quasi-static tensile–shear test is investigated. Microstructure, hardness profile and mechanical performance of the spot welds were studied. Results showed that spot welds are failed in two distinct failure modes: double-pullout and interfacial failure modes. There is a critical fusion zone size beyond which, pullout failure mode is guaranteed. Metallographic examination showed that failure is a competitive process between shear plastic deformation of weld nugget and necking of the base metal. In pullout failure mode, only the grain pattern of the base metal changes significantly and that of the fusion zone and heat affected zone remains unchanged. Strain localization was occurred in the base metal due to its low hardness. Moreover, the experimental results showed that increasing the holding time which increases the hardness of the fusion zone did not affect the peak load. It was concluded that in the pullout failure mode, the strength of the spot welds is not affected by the fusion zone strength. Fusion zone size proved to be the most important controlling factor for the spot welds’ mechanical performance in terms of peak load and energy absorption. [Copyright &y& Elsevier]

Abstract: Epoxy nanocomposites of different content of carbon nanofibers up to 1wt.% have been fabricated under room temperature and refrigerated curing conditions. The composites were studied in terms of mechanical and electrical properties. Flexural modulus and hardness were found to increase significantly in refrigerated samples due to prevention of aggregates of nanofibers during cure condition. Increase and shifting in G-band by Raman spectra of these samples confirmed stress transfer and reinforcement between epoxy matrix and carbon nanofiber. Electrical conductivity improved by 3–6 orders after infusing carbon nanofibers in insulating epoxy. Room temperature samples acquired higher conductivity that was attributed to network formation by aggregates of nanofibers along the fiber alignment direction as revealed by electron microscopic studies. [Copyright &y& Elsevier]

Abstract: 17-4PH stainless steel was plasma nitrocarburized at low temperature for improving its mechanical properties. The results show that the modified layer thicknesses increase with increasing treatment time and the layers growth approximately conforms to the parabolic law. The phases in the modified layers are mainly of incipient γ′-Fe4N and α′-Fe with amorphous characterization, and then changed into γ′-Fe4N, α′N and traces of CrN with the treatment time increasing. The hardness of the nitrocarburized specimen is more than 1280HV, which is about 3.5 times as hard as the untreated one. Meanwhile, the wear resistance of the steel specimen can be dramatically improved by plasma nitrocarburizing. The surface hardness and the wear resistance of the nitrocarburized specimens slightly decrease with an increase in treatment time for the surface hardness as well as microstructure changing. [Copyright &y& Elsevier]

Abstract: Artificial neural network (ANN) is a powerful tool in optimizing many industrial processes. In the present study, an ANN was developed to model and predict the bake hardenability and final yield stress of low carbon steels. Five parameters affecting the bake hardening were considered as inputs, including the annealing/reheating temperature, cooling rate, initial yield stress, work hardening and carbon level. The network was then trained so that to predict the bake hardening amounts and the final yield stress as outputs. A Multilayer cascade-forward back-propagation network is developed and trained using experimental work. Two low carbon steels, St12 and St14, were investigated. The effects of annealing/reheating temperature (500–1000°C) and subsequent cooling rate (0.5, 5 and 500°C/s) on the bake hardenability of steels were modeled by ANN as well. In terms of cooling rate, two different behaviors were observed. The bake hardenability of St12 was increased from 13±2, for reheating to 500°C, to 88±2MPa for the reheating temperature of 1000°C. As for St14, these values were respectively 8±2 and 67±2MPa. The predicted values are in very good agreement with the measured ones indicating that the developed model is very accurate and has the great ability for predicting the bake hardenability. [Copyright &y& Elsevier]

Abstract: The presence of zinc oxide in rubber compounds is tried to be minimized due to environmental concerns. In this study; the effect of different zinc oxide types on ageing properties of SBR compounds was investigated. Active zinc oxide and zinc oxide coat on CaCO3 core were used in SBR compounds and their ageing characteristics were compared. The changes in tensile properties, hardness and rebound resilience were followed and evaluated. [Copyright &y& Elsevier]

Abstract: The mechanical and wear behavior of a series of as-cast gray iron alloys were compared with properties obtained after austempering at 360°C. The austempered alloys showed equivalent or moderately enhanced mechanical strength than the as-cast pearlitic gray irons. The specific wear rates of all the austempered alloys decreased significantly by 7–15 times and friction coefficient reduced by 30–50% compared to pearlitic alloyed gray irons. The dry sliding wear studies of as-cast alloys against high carbon 1%Cr through-thickness hardened steel shows that the specific wear rate ranged from 5.6 to 19.1 (×10−7) g/Nm with friction coefficient from 0.55 to 0.7. While, the austempered alloys showed wear rates from 0.5 to 2.6 (×10−7) g/Nm with friction coefficient ranging from 0.23 to 0.4. The improved wear resistance was attributed to the layer wise surface phase transformation associated with strain induced martensite formation of the stabilized austenite in the austempered matrix, lubrication of the interface by the flake graphite and better heat conduction from the rubbing interface by higher volume fraction of the graphite. Cast iron alloyed with Ni shows enhanced mechanical properties and wear resistance. The tensile strength shows decreasing trend with increase in carbon equivalent and graphite volume. The specific wear rate and friction coefficient shows decreasing trend with increase in hardness and graphite flake volume. [Copyright &y& Elsevier]

Abstract: Carbon black (CB) are commonly added to commercial elastomers for reasons of economy and also to favourably modify properties such as tension, compression, hardness and abrasion, so tension, compression, hardness and abrasion tests were carried out to investigate the effect of CB loading on these properties for Styrene Butadiene Rubber (SBR) and Nitrile Butadiene Rubber (NBR) compounds. The obtained results of five different compositions for SBR and NBR with 0, 20, 30, 50 and 70phr of CB were compared. The dependences of these mechanical properties on CB loading were found. [Copyright &y& Elsevier]

Abstract: In the present paper, the microstructure, compressive properties at different temperatures and hardness of NiAl–Cr(Mo)/Nb alloy prepared by injection-casting were investigated. Compared with the conventionally cast alloy, the injection-cast alloy exhibited a fine microstructure, i.e. the fine eutectic cell and interlamellar spacing as well as fine primary NiAl phase and Laves phase Cr2Nb due to the high cooling rate. In addition, the area fraction of primary NiAl phase at the cell interior or cell boundaries and eutectic cell increased. The compressive ductility and yield strength at room temperature increased by about 100% and 50% over those of conventionally cast alloy, respectively. However, both alloys possessed the similar high temperature strength. The Vickers hardness of injection-cast alloy also increased markedly. [Copyright &y& Elsevier]

Abstract: Aging temperatures play important role in changing the mechanical behavior of rubber, so thermal aging test under different temperatures was carried out to investigate the effect of aging temperatures on the tension, compression and hardness properties of styrene butadiene rubber (SBR) and nitrile butadiene rubber (NBR) compounds filled with different carbon black (CB) loading. The obtained results of five different compositions for SBR and NBR with 0, 20, 30, 50 and 70phr of CB were compared. The dependences of the mechanical properties on aging temperature and CB loading were found. [Copyright &y& Elsevier]

Abstract: Aluminum (Al) matrix composites reinforced with 0–2.0wt.% multi-wall carbon nanotubes (MWCNTs) were prepared by thorough mixing of the composite powders in a roller mill and then sintered using a spark plasma sintering (SPS) machine followed by hot extrusion. Fully dense Al–MWCNT composites were obtained. The microstructure and mechanical properties of these composites were characterized: there is a significant enhancement in the Al–MWCNT composite properties at initial loadings 0.5wt.% of MWCNTs when compared to Al samples without much increase in cost. [Copyright &y& Elsevier]