Advanced Materials for Emerging Applications (Innovations, Improvements, Inclusion and Impact)

Magnesium is the sixth most abundant material in the earth’s crust that finds its applications in the fields of automobiles, aerospace, and biomedical. With noticeable advances in the domain enveloping engineering and technology, there does exist a growing need for new and improved materials to meet the demands put forth by the industries spanning the aerospace and automobile sectors. One of the important requirements for a material is light in weight. Magnesium is one such promising material, which is lighter than aluminum making it an ideal candidate for selection and use in both performance-critical and non-performance critical applications in the domains specific to automobile, aerospace and even biomedical. There are various processing routes for the manufacturing of magnesium alloys, and there exists a need for the joining of the magnesium alloys. The conventional joining processes possess defects, such as porosity, which are detrimental to achieving acceptable to good mechanical properties. Friction Stir welding is one method of solid-state joining, which offers good properties of the weld. The technique of friction stir welding (FSW) operates by rotating and plunging a non-consumable tool into the interface of two workpieces that require to be joined. Promising advantages that are offered by friction stir welding (FSW) are eco-friendly, versatile, and energy efficient. This manuscript highlights (i) the friction stir welding processing technique, as well as recent and observable advances, (ii) the classification of the magnesium alloys, (iii) the welding tool and its influence on welding, microstructural development and mechanical properties of the friction stir welded magnesium alloy, (iv) welding parameters and its influence on governing the relationships between the weld and the workpiece, and (v) typical practical applications and the variants of friction stir welding (FSW).

In the prevailing era, an influential shape memory alloy (SMA) nitinol has emerged as a potentially viable and economically affordable material that is capable of playing a significant role in both existing and emerging technological applications spanning the domains of aircraft and aerospace, biomaterials in bioengineering, sensors in health monitoring, advanced manufacturing, and microelectromechanical systems (MEMS), to name a few. A high strain recovering capability coupled with superelasticity are two key and essential characteristics of a “smart” material that distinguish it easily from its conventional counterparts. The phase transformation behavior shown by nitinol (NiTi) was found to be governed by intrinsic variations in temperature. In order to obtain the desired application-based functionality of this high performing material, potentially viable approaches include the following: (i) an alteration of its chemical composition, (ii) the addition of ternary elements and quaternary elements, and (iii) the use different processing treatments. These approaches are being constantly studied, carefully and systematically examined and frequently reported in the published literature. In this manuscript, an effort is made to present and discuss several of the recent advances specific to the NiTi-based shape memory alloy applications and its phase transformation behaviour when subject to processing treatments. The influence of compositional variation of the NiTi-based shape memory alloys (SMAs) and even its ternary variants and quaternary variants, coupled with the role and/or influence of different processing treatments on both macroscopic properties and microscopic properties is the focus. The emphasis on increasing the suitability of shape memory alloys (SMSs) for selection and use in a spectrum of sensing-related or sensing specific applications is highlighted and briefly discussed.

Shape memory alloys (SMAs) are those that can return to their initial shape after deformation under a stimulus, such as temperature or stress. They are capable of recovering deformations of up to 8%. Generally, the martensitic transformation is reversible in nature and the shape memory alloys exhibit two unique characteristics, super-elasticity effect (SE) and shape memory effect (SME), depending on whether these properties/responses are brought on by stress and temperature, respectively. Since the shape memory alloys undergo full cycling, they transform from austenite to martensite at temperatures between martensite finish and austenite finish. However, partial cycling refers to heating above the austenite start temperature but below the austenite finish temperature followed by cooling to below the martensite finish temperature. The phase transformation is partial before it is complete, consequently, only smaller amounts of the phases undergo a phase transition. Based on the operating temperature window and the transformation temperatures of the alloy, partial cycling can be divided into three categories. This chapter discusses the various types of cycling, i.e., thermomechanical, thermal, and partial cycling behavior of nickel-titanium-based shape memory alloys.

The high-temperature performance of the nitrogen added 316L stainless steels including the high-temperature mechanical properties, workability and weldability have been investigated in detail by systematic studies with nitrogen contents in the range of 0.07-0.22wt.%. Strength and creep resistance were found to increase with increasing nitrogen content at room and elevated temperatures. However, resistance to creep-fatigue damage, fracture toughness, resistance to fatigue crack growth, workability, and weldability were found to degrade beyond 0.14wt% of nitrogen content at service temperature. Therefore, the maximum nitrogen content in 316L stainless steel is recommended to be 0.14wt% for better high-temperature performance in structural applications of fast reactors.

 In the early generation of the Indian 220 MWe pressurized heavy water reactor (PHWR220), Zr-2.5Nb pressure tubes (PT) were manufactured from doublemelted (DM) ingots. Later on, quadruple melted (QM) ingots were used to achieve enhanced performance. These pressure tubes were fabricated by hot extrusion followed by double pilgering with intermediate annealing and this fabrication route is designated as an old route (OR). These tubes have performed reasonably well. However, some of these tubes showed higher in-reactor deformation. Subsequently, both alloy chemistry and manufacturing practice were revisited and changes in alloy chemistry and ingot diameter, mode of hot working for breaking the cast structure and hot extrusion of billets with higher extrusion ratio and single pilgering steps have been employed. This route is designated as a new route (NR) and is being used for manufacturing pressure tubes for the current generation of 220MWe pressurized heavy water reactors.

Over the years, changes in Chlorine (Cl), Carbon (C), Phosphorous (P), Iron (Fe) and Hydrogen (H) specification and narrowing down the specification for Niobium (Nb) and Oxygen (O) have been implemented to exploit their beneficial effect on in-reactor deformation and hydrogen pickup. The changes in manufacturing practices had resulted in changes in microstructure and texture. In the old route (OR), pressure tube (PT) microstructure was characterized by the presence of discrete beta-phase precipitates along the interfaces of alpha lamellae while the new route (NR) pressure tube (PT) exhibits more continuous beta film and relatively coarser α lamellae. In terms of crystallographic texture too, the new route (NR) pressure tubes (PTs) had higher FT values (in the order of 0.65) in comparison to old route (OR) pressure tubes (PTs) (FT~0.55 to 0.6).

Because of crystallographic and microstructural anisotropy, the tensile behavior of this material is also anisotropic with the transverse direction exhibiting higher flow stress and lower ductility at and below reactor operating temperatures. The transverse tensile strength of pressure tube (PTs) fabricated from new route (NR) is higher than that fabricated from old route (OR). The fracture toughness of pressure tubes (PT) manufactured from quadruple melted (QM) ingots are significantly higher than that of the pressure tubes (PTs) manufactured from double melted (DM) ingots, which is attributed to the deleterious effect of Chlorine (Cl), Carbon (C), Phosphorous (P) and their complexes. The variation in fracture toughness of pressure tubes (PTs) was evaluated as a function of temperature, hydrogen content and hydride orientation. The hydrided material exhibited a typical S curve showing lower-shelf, transition and upper shelf regimes. Delayed hydride cracking velocity and threshold stress intensity factor were determined as a function of temperature, direction of approach to test temperature and hydride orientation. Threshold stress for hydride reorientation (σth) determined using ex-situ and in-situ methods between 250 and 300oC was observed to decrease with an increase in temperature. Thermal creep behavior was investigated for these tubes at 350, 400 and 450 °C at different stress levels and comparison of the minimum creep rate and the rupture life is presented. This article describes the evolution of the alloy chemistry, microstructural features, texture and mechanical properties and hydride induced embrittlement of the pressure tubes (PTs) used in Indian pressurized heavy water reactor (PHWR) and life extension approaches. An attempt has been made to rationalize the observed properties in terms of alloy chemistry and microstructure.

Metal matrix composites (MMCs) have proved themselves a reliable alternative to different metals and their alloys due to their high strength-to-weight ratio, high durability; high wear corrosion resistance, high hardness and other mechanical properties. In the conventional approach, different methods like liquid-state processing (stir casting, squeeze casting etc.), solid-state processing (consolidation, physical vapour deposition or PVD, powder bending etc.), and in-situ processing are being used to manufacture metal matrix composites (MMCs). Injection molding and other in-situ processing are highly dependent upon particle size and morphology. Particle agglomeration is a common problem for liquid and solid-state processing. Again, these inhomogeneous second-phase particles influence crack initiation and propagation, thermal mismatches, residual stresses, and dislocation, making the subtracting or machining process challenging to perform. By observing these issues with the conventional approach, additive manufacturing can be considered an alternative technique to fabricating metal matrix composite. It is reported that 3D printing cannot only sort out the matrix/reinforcement bonding issues observed during conventional manufacturing processes but is also capable of providing a uniform distribution of reinforcement inside the metal matrix. Additive manufacturing allows the fabrication of functionally graded composites with any geometrical complexity, higher accuracy, and minimum production lead time. However, challenges like lack of fusion, rapid cooling, poor surface morphology and texture restrict the additive manufacturing processes to manufacturing a sound product. The current chapter summarises the recent development in manufacturing metal matrix composites (MMCs) using different additive manufacturing processes.

The life of human beings is moving at a breakneck pace, with a fast-moving life demanding the need for devices for use in biomedical applications, which attracts the interested researcher to work on ensuring novel breakthroughs. Processing of biomaterials is one of the key factors that will exert an influence on impacting the attributes of a biomaterial. Additive manufacturing is one of the promising routes by which layer-by-layer creation of parts takes place from a computer-aided design (CAD) file. Parts that cannot or are difficult to manufacture by other processing routes can be easily manufactured using the technique of additive manufacturing (AM). Parts, such as (i) stents, (ii) customized prosthetics, (iii) organs, and (iv) implants can be easily manufactured using the technique of additive manufacturing (AM). With noticeable advances in the domain specific to additive manufacturing, the biomedical field is being revolutionized, and viable solutions to difficult problems are being put forth with ease, and the resultant by-products offer a combination of acceptable to good properties. The key benefits of the technique of additive manufacturing (AM) are low cost, minimal material waste, and enhanced product reliability. This study explores recent developments in both alloys and composite materials processed by the techniques of additive manufacturing for selection and use in biomedical applications. This review provides a highlight of the different additive manufacturing techniques with specific reference to biomedical applications and additive manufacturing of titanium alloys, the Co-Cr alloy, the magnesium alloys and their composite counterparts. Multidisciplinary research will be required to meet and overcome any and all obstacles while concurrently fulfilling the potential of additive manufacturing (AM) in the years ahead.

The limitations of engineering are mainly attributed to the limitations in the availability of materials that can deliver all the desired properties for a given end application. But, due to the development of composites, there has been an enormous advancement in industries like automobile, sports, power generation, defense, and aerospace. Metal Matrix Composites became one of the sought-after materials because of their high specific properties, such as strength-to-weight ratio. Even though these materials exhibit enhanced mechanical and thermal properties, their usage is still limited. Some of the reasons include the scaling up of processing and the uncertainty in their joining and corrosion behavior. This study attempts to bring together information on metal matrix composites processing and corrosion behavior, mainly focusing on Magnesium and Aluminum metal matrix composites.

Aluminium has a lightweight (density is 2.7 g/cm3 ), high specific strength, and excellent wear and corrosion resistance properties. Due to these properties, aluminium and its alloys are the most commonly used for structural, automobile, and aerospace applications. However, these monolithic materials have poor mechanical properties which are significant barriers to their further development. The resulting materials, when reinforced with ceramic particles, enhance the properties of materials and are capable of meeting the majority of industrial requirements. The reinforcement of ceramic affects the properties of developed composites. The composite fabricated by the conventional process has a limitation to the segregation of reinforced ceramic particles, porosity, weak interfacial bonding, and lower strength. Besides, additive manufacturing (AM) provides design freedom and dense and high-strength components. In the present study, advances in aluminium nanocomposite developed by laser powder bed fusion processes have been studied in detail. In addition, the objective of this chapter is to focus on the fabrication routes, formation mechanisms, effect of process parameters and its effect on laser absorption, grain refinement, interfacial bonding and mechanical properties of aluminium nanocomposite discussed in detail. The future scope of laser-processed aluminium composite is also briefly discussed.

We report here a significant enhancement of the hardness of aluminumboron carbide composites by the addition of magnesium. Reactive sintering between boron carbide and aluminum-magnesium occurs by the application of heat and pressure and during subsequent annealing at high-homologous temperatures of the matrix. In this case, the deformation-induced plastic yielding enables the incorporation and dispersion of hard particles in aluminum-matrix. We examine the decomposition behavior of boron carbide at high-homologous temperatures in contact with magnesium and aluminum, and observe the interfacial, aluminum-magnesium-boride, AlMgB4 , and aluminum-boro-carbide, Al3BC, phases at boron carbide/matrix interfaces as revealed by the high-resolution transmission electron microscopy. We demonstrate that the hardness of these composites has been enhanced by two to five folds as compared to the base alloy and the existing aluminum-boron carbide composites. The addition of magnesium improves interfacial cohesion significantly between the matrix and ceramic particles as a result of interfacial boride phase, and primarily contributes to the enhancement of strength. This provides a novel method of developing aluminum-based high strength composites. 

This study provides a short, succinct and convincing review of the studies researchers have performed on sisal natural fibre and its applicability for selection and use as a potentially viable and economically affordable reinforcement for engineering composite materials. As the technologies are developing rapidly day by day and the demand for developing and manufacturing eco-friendly materials is also increasing, the use of the bio-degradable reinforcements, like bamboo, sisal, jute, cotton and hemp, is of utmost concern. Made evident from a few to several other research studies, in comparison to the fabricated natural fibre-reinforced composite materials, the sisal fibres indicate considerable results that favour their applicability. Environmental contamination happens in various aspects of industrial processes, such as production, disposal, and recycling of synthetic fiber-reinforced composites due to their widespread selection and use. Sisal fiber is a good example of an environmentally acceptable natural fiber having significant mechanical qualities, which can be utilized for reinforcing a variety of polymer matrices. This review article provides a coverage of the intricacies specific to the manufacture of sisal fiber-reinforced composite materials, variables that impact their characteristics, surface treatments used to prevent the presence of flaws, and mechanical tests required to determine their strength. Prior testing attempts on the sisal fiber-reinforced composites are addressed in order to aid in future research to reveal the advantages and usage of such a material in a more effective and efficient manner. The current era of rapidly changing manufacturing environment and technological advancements highlighting such scenarios calls for a substantial amount of research to be performed on: (i) structure of sisal fibre, (ii) sisal fibre extraction/preparatory processes, and (iii) surface treatments of sisal fibres combined with other matrices.

The selection of suitable biomaterials and implants is the most important criterion to achieve success in biomedical engineering. Several factors such as high specific strength, high corrosion resistance, enhanced wear resistance, biodegradability, and biocompatibility need to be considered before choosing the material for biomedical applications. The biomaterials are developed from metals, metal alloys, ceramics, and polymers based on specific applications. In the orthopedic field, inert materials have been used in earlier times that showed minimal cell-material interaction, and bioinert materials were preferred to avoid immune rejection and increase the success rate. Metallic alloys such as Ti-6Al-4V, 316 stainless steel, and cobalt-chromium are frequently used in the fabrication of bone implants. Metal alloys have problems like corrosion and are less bioactive. In recent years, the concept of regeneration has been developed and it is entirely based on cell-material interactions, and the selected materials need to exert bioactivity. Regenerative materials are prepared from biodegradable metals, polymers, and ceramics. Numerous techniques have been developed recently to convert a bioinert material into bioactive or regenerative material. Smart materials and implants with bioactive surfaces are also getting more attention in the orthopedic field. This chapter throws light on two fields that have contributed to bone replacement and regeneration. An overview of the bioinert implants in the orthopedic industry and the current development of bioinert into bioactive and immunomodulating materials will be discussed. The future aspects describe the role of smart materials for bone regeneration in detail. 

Smart and intelligent materials provide direct or indirect solutions for many of the current/existing problems. Studies in this line have been in progress since few decades developing multifunctional materials, smart systems etc., for specific applications. Though many smart materials were developed, not much of them are compatible as implants in human body. One such material that possesses the inherent requirements attuned with human body is ‘hydrogel’. Like other smart materials, gels can also be intelligent in their responses to the environments they are exposed to, or on influence of any induced stimuli. Many such smart gels are explored by various industries and are used for applications such as drug delivery systems, cancer therapy, tissue engineering and organ printing, but a comprehensive understanding with properties, and their mechanisms regarding their functionality and usage are meagre. This work consolidates and details the classification of gels and elaborates the various stimuli to which gels respond and the mechanisms involved. This article also explores the possibilities, prospects of 3D-printing of smart gels in biomedical field and has listed the possible applications of hydrogels.

Ferrite nanomaterials are extensively studied for their use in the biomedical field primarily because of their tunable magnetic properties and biocompatibility. The use of magnetic nanomaterials, particularly the iron-based nanoparticles, for hyperthermia treatment is one of the emerging applications. However, there are practical constraints on the overall applicability of pure iron-oxide nanoparticles (IONPs) for hyperthermia treatment. In this regard, doping foreign metal ions in the crystal lattice of pure iron-oxide nanoparticles (IONPs) possessing a spinel or inversespinel structure remains to be the simplest approach for the purpose of improving the desired properties. Doping other metal ions into the iron-oxide nanoparticles (IONPs) causes strain in the crystal lattice and is responsible for engineering the structural properties and magnetic properties. Various elements, such as the rare-earth (RE) metals, especially the lanthanides [Yttrium, Gadolinium and Europium], the transition metals [manganese, cobalt, nickel and zinc], and other metals [gold, silver, calcium, titanium, copper and magnesium] are being investigated for their potential to serve as dopants. The divalent transition metals [manganese, cobalt and nickel] doped ironoxide nanoparticles possess highly improved magnetic properties. Incorporating trivalent ions of lanthanides improves the structural properties, magnetic properties, and dielectric properties of the iron-oxide nanoparticles (IONPs). Moreover, doping with zinc, gold and silver imparts the ion-oxide nanoparticles (IONPs) with antibacterial properties while concurrently tuning their structural properties and magnetic outputs.

Residential, workplace, commercial & wildfires claim and injure millions of people and cause trillions of dollars worth of property damage worldwide, considering both natural & man-made resources. The current review paper provides a clean, clear, cohesively complete and convincing review of the emergence of new and sustainable emergent material additives that improve fire-retardant properties and thermal stability, as well as their applications for the safety and protection of life and property in buildings. Globally emerging materials have entered the realms of construction, protection of critical apparatus, and self-protection equipment, thereby revolutionizing the level of fire protection for both people and materials. However, cost, application difficulty, mass-scale availability, and a lack of knowledge have frequently led to a lack of focus on preventing this calamity. In addition, emerging materials technologies can contribute to sustainable development by considerably enhancing the fire-retardant properties of recyclable waste, including both biological waste and industrial waste.

Nowadays, numerous metallic alloys are known to exhibit smart behavior; these metallic materials are categorized as shape memory alloys (SMAs). Shape memory alloys belong to a group of smart alloys that have the potential to recover their original shape from a deformed shape when triggered by factors, such as heat, electricity, and stress. This shape change gives rise to SMART behavior (Stimulated Martensite - Austenite Reverse Transformation). Shape memory alloys have attractive characteristics, such as high recovery force, high strength, etc. Shape memory alloys find their use in many applications i.e., aerospace, biomedical, automobile, robotics, etc. The ever-increasing demand for shape memory alloys among industries is attributed to their ability to respond to different machining processes. Conventional machining processes (CM) and unconventional machining (UCM) processes are the two major types of processes upon which the studies on shape memory alloys have been carried out. The machining studies carried out reveal that the use of conventional machining to process shape memory alloys to various products is considered undesirable since it causes damage and introduces changes in the characteristics of the material. Unconventional machining processes are therefore preferred. Various types of unconventional machining processes like laser beam machining (LBM), electrodischarge machining (EDM), electrochemical machining (ECM), abrasive jet machining (AJM), abrasive water-jet machining (AWJM), etc., generally involve machining of shape memory alloys in an unconventional way so that the wear rate and surface roughness are reduced. A study of unconventional machining processes is therefore considered essential contributing further to the domain of smart materials. Hence, through this review, the mechanism of shape memory alloys and their applications, various types of unconventional machining processes, and their recent advances are highlighted.

Strength and ductility of materials at high strain rate of deformation are important for design engineers working in a wide range of industries, especially in gas turbine engine blades. Split Hopkinson pressure bar (SHPB) apparatus is a popular method of characterizing the high strain rate behaviour of materials. The results from the split-Hokinson pressure bar tests are further used in mathematical models such as Johnson-Cook model, Zerelli - Armstrong model and so on for correlation purposes. Split-Hopkinson pressure bar tests take place in a very short duration of time (less than a second) but require significant effort in arranging the apparatus (several hours to days) and replications could be a daunting task. The present review work focuses on some of the critical test parameters that influence the test results. Specimen dimensions, its alignment in the split-Hopkinson pressure bar apparatus and location of strain gauges are critical parameters to be checked before the test (pre-testing) while selecting the accurate signal data processing technique (post-testing) to filter the noise which is critical to get meaningful test results. This review work focuses on the effect of three pre-testing parameters and signal data processing techniques on the high strain rate test results and summarizes the salient findings.