New Class Of Engineering Materials Research Articles

Fluorescence-based thermal sensing with elastic organic crystals

Operation of temperature sensors over extended temperature ranges, and particularly in extreme conditions, poses challenges with both the mechanical integrity of the sensing material and the operational range of the sensor. With an emissive bendable organic crystalline material, here we propose that organic crystals can be used as mechanically robust and compliant fluorescence-based thermal sensors with wide range of temperature coverage and complete retention of mechanical elasticity. The exemplary material described remains elastically bendable and shows highly linear correlation with the emission wavelength and intensity between 77 K to 277 K, while it also transduces its own fluorescence in active waveguiding mode. This universal new approach expands the materials available for optical thermal sensing to a vast number of organic crystals as a new class of engineering materials and opens opportunities for the design of lightweight, organic fluorescence-based thermal sensors that can operate under extreme temperature conditions such as are the ones that will be encountered in future space exploration missions.

Characterization of machinability of sintered steel foams having different porosities during drilling operations

Steel foams are a new class of engineering materials with exceptional structure and properties. Foams produced by powder metallurgy generally have a near-net shape, however, sometimes machining operations may be required. The presence of porosity in steel foams significantly affects the cutting process and causes poor machinability. This study deals with the evaluation of the machinability of Cu-Ni-Mo-based steel foams having different porosity produced by powder metallurgy. High speed steel and carbide-tipped drills were used for the drilling. All tests were performed in dry condition with drill diameter of 3 mm. The drilling characteristics were evaluated in terms of the surface roughness, chip formation, drilling force, tool wear, microstructure and hardness change after drilling. The machinability was also evaluated by measuring average width of breakout and skewness values of the hole drilled. The results indicated that the increase of porosity negatively affected the drilling quality of high porous steels. Both drills broke the chips in powder form and produced discontinuous chips. High porous parts exhibited higher hardness change as compared to lower ones. The carbide drill showed acceptable drilling forces and surface quality. HSS drill is not suitable for drilling due to poor hole quality and high drill wear. Highlights Steel foams exhibit poor machinability due to highly porous structure. Porosity and tool type significantly affect the surface integrity of steel foams. Surface roughness and drill wear increased with increasing porosity; however, feed force decreased. Intense presence of pores decreases the tool life remarkably. The skewness values of hole are positive in all porosities. Carbide-tipped drill produced the finest hole quality. The larger damage was observed at the exit of the drilled holes with HSS drill.

Effect of Graphene nanoparticles on microstructural and mechanical properties of aluminum based nanocomposites fabricated by stir casting

Purpose The development of a new class of engineering materials is the current demand for aircraft and automobile companies. In this context metal, composite materials have a widespread application in different areas of manufacturing sectors. Design/methodology/approach In this paper, an attempt is made to develop the aluminium-based nano metal matrix composite reinforced with graphene nanoparticles (GNP) by using the stir casting method. Different weight percentage (0.4%, 0.8% and 1.2% by weight) of GNPs are used to fabricate metal matrix composites (MMCs). The developed nanocomposites were further validated by density calculation and optical microstructures to discuss the distribution of GNPs. The tensile test was conducted to determine the strength of the developed MMCs and also supported by fractographic analysis. In addition to it, the Rockwell hardness test and impact test (toughness) with fracture analysis were also conducted to strengthen the present work. Findings The results reveal the uniform distribution of GNPs into the matrix material. The yield strength and ultimate tensile strength obtained a maximum value of 155.67 MPa and 170.28 MPa, respectively. The hardness value (HRB) is significantly increased and 84 HRB was obtained for the sample with AA1100/0.4% GNP, while maximum hardness value (94 HRB) was obtained for the sample AA1100/1.2% GNP. The maximum value of toughness 14.3 Jules/cm2 is recorded for base alloy AA1100 while increasing the reinforcement percentage, it decreases up to 9.7 Jules/cm2 for AA1100/1.2% GNP. Originality/value Graphene nanoparticles are used to develop nanocomposites, which is one of the suitable alternatives for heavy engineering materials such as steels and cast irons. It has improved microstructural and mechanical properties which makes it preferable for many engineering and structural applications.

Metal matrix composites- a review on synthesis and characterization

The manufacturing industries continuously demanded the new class of engineering materials for various applications. It results in improvement of metal matrix composites. Development of newer materials like MMCs are one of the keen area of research now a day’s. In this regard various literatures are available in open literature on development, characterization and application of MMCs. In this work an attempt is made to discuss the available literatures in terms of their output findings. The work also focuses on the area where the more attention is required to carry out the research work.

Mechanisms of compressive deformation and failure of porous bulk metallic glasses

Bulk metallic glasses (BMGs) are a new class of engineering materials having strengths as high as 10 times that of conventional steels, but show no significant plastic strain at fracture. By introducing pores, their strain to failure has been shown to improve under uniaxial compression. In this work, three-dimensional finite element simulations of uniaxial compression are carried out on Pd-based porous BMGs having a wide range of pore volume fraction (1.9%–60%) with emphasis on understanding the underlying deformation and failure mechanisms. The resulting stress–strain curves agree reasonably well with existing experimental results. The simulations clearly bring out different failure mechanisms in low porosity BMGs and high porosity BMG foams. For low porosity BMGs (below 20%), the deformation and failure involves nucleation of shear bands around the pore diameter, linking of the shear bands with adjacent pores finally leading to initiation of ductile cracking within the shear bands. For high porosity BMG foams, the mechanism of deformation involves reduction in porosity of the material, self-contact of the pores, and their collapse on themselves causing densification of the material leading to apparent hardening in the stress strain behavior. The effect of pore geometry is also studied by considering ellipsoidal pores of volume fraction 3% and 11%. For ellipsoidal pores, the failure mechanisms are found to differ significantly when the orientation of the major axis of the pore vis-a-vis the loading axis is changed.

Analytical modeling of effect of interlayer on effective moduli of layered graphene-polymer nanocomposites

Nanocomposites enhanced with two-dimensional, layered graphene fillers are a new class of engineering materials that exhibit superior properties and characteristics to composites with conventional fillers. However, the roles of “interlayers” in layered graphene fillers have yet to be fully explored. This paper examines the effect of interlayers on mechanical properties of layered graphene polymer composites. As an effective filler, the fundamental properties (in-plane Young’s modulus EL1, out-of-plane Young’s modulus EL2; shear modulus GL12, major Poisson’s ratio νL12) of the layered graphene were computed by using the Arridge’s lamellar model. The effects of interlayers on effective moduli of layered graphene epoxy composites were examined through the Tandon-Weng model. The properties of the interlayer show noticeable impact on elastic properties of the composites, particular the out-of-plane properties (Young’s modulus E2 and shear modulus G12). The interlayer spacing is seen to have much great influence on properties of the composites. As the interlayer spacing increases from 0.34nm to 2nm, all elastic properties of the composites have been greatly decreased.

A New Class of Engineering Materials: Particle-Stabilized Metallic Emulsions and Monotectic Alloys

Al-matrix particulate composites are melted and mixed with immiscible metals to form their small droplets in liquid aluminum. It is shown that, in the Al-Si/SiC/Bi system, the Bi droplets are stabilized by the SiC particles in the liquid Al matrix. Upon solidification, homogeneous distribution of solidified Bi droplets is obtained in the Al matrix at the bottom part of the ingot. Thus, a new class of engineering materials (particle-stabilized monotectic alloys) is obtained.

Designing metallic glass matrix composites with high toughness and tensile ductility

The selection and design of modern high-performance structural engineering materials is driven by optimizing combinations of mechanical properties such as strength, ductility, toughness, elasticity and requirements for predictable and graceful (non-catastrophic) failure in service. Highly processable bulk metallic glasses (BMGs) are a new class of engineering materials and have attracted significant technological interest. Although many BMGs exhibit high strength and show substantial fracture toughness, they lack ductility and fail in an apparently brittle manner in unconstrained loading geometries. For instance, some BMGs exhibit significant plastic deformation in compression or bending tests, but all exhibit negligible plasticity (<0.5% strain) in uniaxial tension. To overcome brittle failure in tension, BMG-matrix composites have been introduced. The inhomogeneous microstructure with isolated dendrites in a BMG matrix stabilizes the glass against the catastrophic failure associated with unlimited extension of a shear band and results in enhanced global plasticity and more graceful failure. Tensile strengths of approximately 1 GPa, tensile ductility of approximately 2-3 per cent, and an enhanced mode I fracture toughness of K(1C) approximately 40 MPa m(1/2) were reported. Building on this approach, we have developed 'designed composites' by matching fundamental mechanical and microstructural length scales. Here, we report titanium-zirconium-based BMG composites with room-temperature tensile ductility exceeding 10 per cent, yield strengths of 1.2-1.5 GPa, K(1C) up to approximately 170 MPa m(1/2), and fracture energies for crack propagation as high as G(1C) approximately 340 kJ m(-2). The K(1C) and G(1C) values equal or surpass those achievable in the toughest titanium or steel alloys, placing BMG composites among the toughest known materials.

Structural and mechanical properties of titanium and titanium diboride monolayers and Ti/TiB 2 multilayers

Nano-multilayers represent a new class of engineering materials that are made up of alternating nanometer scale layers of two different components. In the present work a titanium (Ti) monolayer was combined with titanium diboride (TiB 2) to form a Ti/TiB 2 nano-multilayer. Designed experimental parameters enabled an evaluation of the effects of direct current bias voltage ( U b) and bilayer thickness ( Λ) during multilayer deposition on the mechanical properties of reactively sputtered Ti/TiB 2 multilayer films. Their nanostructures and mechanical properties were characterized and analyzed using X-ray photoelectron spectroscopy (XPS), low-angle and high-angle X-ray diffraction (XRD), plan-view and cross-sectional high-resolution transmission electron microscopy (HRTEM), and microindentation measurements. Under the optimal bias voltage of U b = − 60 V, it was found that Λ (varied from 1.1 to 9.8 nm) was the most important factor which dominated the nanostructure and hardness. The hardness values obtained varied from 12 GPa for Ti and 15 GPa for TiB 2 monolayers, up to 33 GPa for the hardest Ti/TiB 2 multilayer at Λ = 1.9 nm. The observed hardness enhancement correlated to the layer thickness, followed a relation similar to the Hall-Petch strengthening dependence, with a generalized power of ∼ 0.6. In addition, the structural barriers between two materials (hcp Ti/amorphous TiB 2) and stress relaxation at interfaces within multilayer films resulted in a reduction of crack propagation and high-hardness.

State of the Art: Applications of Mechanically Alloyed Nanomaterials—A Review

Nanostructured materials as a new class of engineering materials with enhanced properties and structural length scale between 1 and 100 nm can be produced by a variety of different methods. Mechanical alloying (MA) technique is one of the processes to produce nanomaterials. This process involving milling of constituent powder in high-energy ball mills goes extensive mechanical deformation due to ball-powder-ball and ball-powder-container collisions that occur during MA. The development of strong oxide dispersion strengthened (ODS) alloys has been the prime goal of Benjamin's group, which invented the MA technique. But, the possibility of synthesizing a variety of materials has made MA an exciting field to work in for many investigators. Mechanically alloyed nickel-based, iron-based superalloys, and aluminum-based alloys are in commercial production. The ODS Al-base alloys made by MA are found to be much superior to the traditional alloys in term of strength and hardness value even at high temperature. The mechanical alloying process attracts the attention of a large group of researchers and technologists basically because of its potential to produce a variety of materials in the simplest possible way. MA definitely has a bright future as a solid-state processing route.

A Practical Thermodynamic Method to Calculate the Best Glass-forming Composition for Bulk Metallic Glasses

Bulk metallic glasses are regarded as a new class of engineering materials because of their extraordinary high strength, great elasticity, and high corrosion and wear resistance. The selection of good glass-forming composition is the most important issue in BMG development. In this paper, a thermodynamic method, which combines element substitution and mixing enthalpy calculation, has been successfully developed to predict the optimum glass-forming compositions in Cu-Zr-Ti, Cu-Hf-Ti, Cu-Zr-Hf-Ti and Pd-Ni-P alloy systems. Alloy compositions with the largest glass-forming ability are always accompanied with the smallest enthalpy value for the alloy systems. The prediction results have been confirmed by experiments. It is concluded that the thermodynamic method provides a practical and effective tool to find the optimum glass forming composition.

Reaction sintering of NiAl and TiB2–NiAl composites under pressure

Intermetallic matrix composites are a new class of engineering materials for high temperature structural applications in oxidizing and aggressive environments. Attempts have been made in the present investigation to synthesize TiB2–NiAl composites, in which the matrix phase NiAl was produced in situ by reaction synthesis. The composites with 10, 15 and 30 vol.%NiAl were fabricated from the mixtures of elemental Ni and Al and TiB2 powders by high pressure reaction sintering (HPRS) and reactive hot pressing (RHP). The HPRS and RHP were carried out at 3 GPa and 900°C, and 20 MPa and 1650°C, respectively. The different phases in the sintered compacts were identified by X-ray diffraction and microstructural studies. In HPRS, the reaction was incomplete which gave rise to various intermediate phases (Ni2Al3, Ni3Al). It was necessary to anneal these compacts at 1100°C to obtain TiB2–NiAl composites with single phase NiAl matrix. The densities of the HPRS compacts were ∼99%. The hardness and fracture toughness values were in the range 10 to 20 GPa and 3.9 to 5.7 MPa√m, respectively. The RHP compacts contained AlB2, Ni2B and NiTi2 phases in addition to those present in the HPRS compacts. The RHP composites were fully dense. These had superior hardness (15–22 GPa) but inferior fracture toughness (2.9–3.8 MPa√m) compared to those obtained by HPRS.

Change in structure and properties during solid sintering of Ni-Al powders : Y.Ito et al. (University of Hokkaido, Hokkaido, Japan.) Mater. Trans. JIM, vol 37, no 4, 1996, 1067–1972

Intermetallic matrix composites are a new class of engineering materials for high temperature structural applications in oxidizing and aggressive environments. Attempts have been made in the present investigation to synthesize TiB2–NiAl composites, in which the matrix phase NiAl was produced in situ by reaction synthesis. The composites with 10, 15 and 30 vol.%NiAl were fabricated from the mixtures of elemental Ni and Al and TiB2 powders by high pressure reaction sintering (HPRS) and reactive hot pressing (RHP). The HPRS and RHP were carried out at 3 GPa and 900°C, and 20 MPa and 1650°C, respectively. The different phases in the sintered compacts were identified by X-ray diffraction and microstructural studies. In HPRS, the reaction was incomplete which gave rise to various intermediate phases (Ni2Al3, Ni3Al). It was necessary to anneal these compacts at 1100°C to obtain TiB2–NiAl composites with single phase NiAl matrix. The densities of the HPRS compacts were ∼99%. The hardness and fracture toughness values were in the range 10 to 20 GPa and 3.9 to 5.7 MPa√m, respectively. The RHP compacts contained AlB2, Ni2B and NiTi2 phases in addition to those present in the HPRS compacts. The RHP composites were fully dense. These had superior hardness (15–22 GPa) but inferior fracture toughness (2.9–3.8 MPa√m) compared to those obtained by HPRS.

MMCX—An expert system for metal matrix composite selection and design

Metal Matrix Composites (MMCs) are a relatively new class of engineering materials that offer the designer an opportunity to tailor properties to meet specific requirements. The paper summarizes the development of an expert system which supports engineers in the selection and design of metal matrix composites. The system consists of a dynamic hypertext interface integrated into an expert system developed within the COMDALE/X environment. Mechanical and thermophysical property data for matrix alloys, reinforcement materials, and MMCs are stored in databases accessed by the expert system. Mathematical models which utilize constituent material properties to determine effective composite properties are managed by the system to design metal matrix composites and fill property gaps. Effective elastic modulus, thermal conductivity, coefficient of thermal expansion. Poisson's ratio, shear and bulk moduli mathematical models for particulate, whisker, short fiber and fiber composites are contained in a spread sheet managed by the system. Although the physical and mechanical properties may often limit the constituent selection, it is the chemical reactivity of the ceramic reinforcement with the matrix alloy either during fabrication or service which will generally control the final matrix/reinforcement combination. As a result, constituent material compatibility has been determined and incorporated in the system. A database of appropriate reinforcement coatings for applicable matrix/reinforcement systems is also helpful. The system also includes information on suitable manufacturing techniques. A case study demonstrating the use of the system for selecting an MMC for cryogenic applications is presented.

Status and Development of Nickel Aluminide (NiAl) Composites

AbstractNiAl-based composites are a new class of engineering materials being developed for high temperature structural applications in oxidizing and aggressive environments. This paper discusses some of the recent advances in developing continuous fiber-reinforced polycrystalline NiAl-based composites. Several key issues including matrix alloy development, fiber development, fabrication development and mechanical behavior will be addressed.

Calorimetric and morphological studies or mechanically alloyed and mechanically disordered aluminium alloys with transition metals: M.S. El-Eskandarany et al (Tohoku Univerity, Sendai, Japan), J Japan Soc Powder and Powder Metallurgy, Vol 39, No 10, 1992, 836–841

Intermetallic matrix composites are a new class of engineering materials for high temperature structural applications in oxidizing and aggressive environments. Attempts have been made in the present investigation to synthesize TiB2–NiAl composites, in which the matrix phase NiAl was produced in situ by reaction synthesis. The composites with 10, 15 and 30 vol.%NiAl were fabricated from the mixtures of elemental Ni and Al and TiB2 powders by high pressure reaction sintering (HPRS) and reactive hot pressing (RHP). The HPRS and RHP were carried out at 3 GPa and 900°C, and 20 MPa and 1650°C, respectively. The different phases in the sintered compacts were identified by X-ray diffraction and microstructural studies. In HPRS, the reaction was incomplete which gave rise to various intermediate phases (Ni2Al3, Ni3Al). It was necessary to anneal these compacts at 1100°C to obtain TiB2–NiAl composites with single phase NiAl matrix. The densities of the HPRS compacts were ∼99%. The hardness and fracture toughness values were in the range 10 to 20 GPa and 3.9 to 5.7 MPa√m, respectively. The RHP compacts contained AlB2, Ni2B and NiTi2 phases in addition to those present in the HPRS compacts. The RHP composites were fully dense. These had superior hardness (15–22 GPa) but inferior fracture toughness (2.9–3.8 MPa√m) compared to those obtained by HPRS.

Preparation of amorphous metal powder by mechanical alloying: M. Fedorcakonva and M. Micskovicova, (Ustav Materialaveho Vyskumu SAV, Kosice, Czechoslovakia), Pokroky Psaskove Metallurgie, No 1–2, 1992, 40–51. (In Czech)

Intermetallic matrix composites are a new class of engineering materials for high temperature structural applications in oxidizing and aggressive environments. Attempts have been made in the present investigation to synthesize TiB2–NiAl composites, in which the matrix phase NiAl was produced in situ by reaction synthesis. The composites with 10, 15 and 30 vol.%NiAl were fabricated from the mixtures of elemental Ni and Al and TiB2 powders by high pressure reaction sintering (HPRS) and reactive hot pressing (RHP). The HPRS and RHP were carried out at 3 GPa and 900°C, and 20 MPa and 1650°C, respectively. The different phases in the sintered compacts were identified by X-ray diffraction and microstructural studies. In HPRS, the reaction was incomplete which gave rise to various intermediate phases (Ni2Al3, Ni3Al). It was necessary to anneal these compacts at 1100°C to obtain TiB2–NiAl composites with single phase NiAl matrix. The densities of the HPRS compacts were ∼99%. The hardness and fracture toughness values were in the range 10 to 20 GPa and 3.9 to 5.7 MPa√m, respectively. The RHP compacts contained AlB2, Ni2B and NiTi2 phases in addition to those present in the HPRS compacts. The RHP composites were fully dense. These had superior hardness (15–22 GPa) but inferior fracture toughness (2.9–3.8 MPa√m) compared to those obtained by HPRS.

Production and properties of mechanically alloyed nickel aluminides: S. Ochiai and Y. Kojima (Nishi University of Tokyo, Yamanashi, Japan), J Japan Soc Powder and Powder Metallurgy, Vol 39, No 10, 1992, 891–896. (In Japanese)

Intermetallic matrix composites are a new class of engineering materials for high temperature structural applications in oxidizing and aggressive environments. Attempts have been made in the present investigation to synthesize TiB2–NiAl composites, in which the matrix phase NiAl was produced in situ by reaction synthesis. The composites with 10, 15 and 30 vol.%NiAl were fabricated from the mixtures of elemental Ni and Al and TiB2 powders by high pressure reaction sintering (HPRS) and reactive hot pressing (RHP). The HPRS and RHP were carried out at 3 GPa and 900°C, and 20 MPa and 1650°C, respectively. The different phases in the sintered compacts were identified by X-ray diffraction and microstructural studies. In HPRS, the reaction was incomplete which gave rise to various intermediate phases (Ni2Al3, Ni3Al). It was necessary to anneal these compacts at 1100°C to obtain TiB2–NiAl composites with single phase NiAl matrix. The densities of the HPRS compacts were ∼99%. The hardness and fracture toughness values were in the range 10 to 20 GPa and 3.9 to 5.7 MPa√m, respectively. The RHP compacts contained AlB2, Ni2B and NiTi2 phases in addition to those present in the HPRS compacts. The RHP composites were fully dense. These had superior hardness (15–22 GPa) but inferior fracture toughness (2.9–3.8 MPa√m) compared to those obtained by HPRS.

Carbon Carbon Composites: An Overview .

Carbon carbon composites are a new class of engineering materials that are ceramic in nature but exhibit brittle to pseudoplastic behaviour. Carbon-carbon is a unique all-carbon composite with carbon fibre embeded in carbon matrix and is known as an inverse composite. Due to their excellent thermo-structural properties, carbon-carbon composites are used in specialised application like re-entry nose-tips, leading edges, rocket nozzles, and aircraft brake discs apart from several industrial and biomedical applications. The multidirectional carbon-carbon product technology is versatile and offers design flexibility. This paper describes the multidirectional preform and carbon-carbon process technology and research and development activities within the country. Carbon-carbon product experience at DRDL has also been discussed. Development of carbon-carbon brake discs process technology using the liquid impregnation process is described. Further the test results on material characterisation, thermal, mechanical and tribological properties are presented.