2D materials are emerging as ideal candidates for fundamental investigations and new technologies due to their unique optoelectronic properties. Giant nonlinear susceptibility and perfect phase matching in 2D materials lead to extraordinary nonlinear light matter interactions, thus enabling several potential applications and fundamental scientific discoveries in nonlinear optics. For instance, second harmonic generation in 2D materials play an important role in optical devices such as, lasers, tunable waveguides, electro‐optic modulators, and switches. This review will discuss optical harmonic generation (OHG) processes, various characterization modes, and tuning techniques in 2D materials. The future prospectives for OHG in 2D materials is discussed. The extremely promising attributes of combining nonlinear optics and 2D materials is becoming a highly important multidisciplinary field.

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Titanium alloys, especially Ti-6Al-4V, which is considered a difficult-to-cut material, bears numerous applications in aerospace and biomedical sectors. The criticality of the accurate formation of the machined cavity for the said applications and properties of Ti-6Al-4V accentuated the use of electric discharge machining (EDM). However, the issues of lower material removal rate (MRR) and tool wear (TWR) discouraged the use of EDM. These inherent issues hold a pivotal role regarding the sustainable machining of Ti-alloy. Therefore, in this research the potentiality of kerosene-based dielectric, having graphene nanoparticles, is comprehensively examined for the sustainable EDM of Ti-6Al-4V, which was not focused upon yet. Experimentation was performed under Taguchi’s design (L18) with three types of electrodes, namely Aluminum, Brass and Copper. In total, 36 experiments were conducted, of which 18 were with graphene-mixed dielectric and the remaining were with kerosene. Experimental results reveal that the brass electrode with negative tool polarity yields higher MRR for both types of dielectrics. The maximum MRR (7.602 mm3/min) achieved with graphene mixed dielectric is 64.5% greater as compared to that obtained with kerosene (4.621 mm3/min). Moreover, the minimum TWR obtained for graphene-based dielectric, i.e., 0.17 mg/min is approximately 1.5 times less than that achieved with kerosene.

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Ti-6Al-4V is a material of high interest in various industrial sectors including biomedical, automotive and aerospace. Conventional means of machining encounter different types of difficulties. Electric discharge machining (EDM) is not a contest of hardness. Circular impressions of micro-depth are produced in Ti-6Al-4V using four different electrode materials including aluminum, brass, graphite and copper, each assigned positive and negative polarity. In order to get precise control over the geometry of micro-impressions dimensional accuracy and tool wear must be controlled. Thus, EDM performance has been evaluated in terms of axial dimensional error (D.E_Axi), radial dimensional error (D.E_Rad), tool length reduction (TLR), and surface roughness (SR). Since the EDM process is stochastic in nature therefore in addition to tool polarity only two factors are considered as variables, i.e. discharge current and pulse-time-ratio (ration of on-time to off-time). The behaviors of each of the four electrode materials are compared together under each of the two polarities and two variables for each of the four response characteristics. The search is carried out to select the most appropriate tool electrode polarity (common for all responses) and a single common electrode capable of minimizing all the four response measures simultaneously. Moreover, microstructures of the machined impressions are discussed. Without any compromise in the minimum values of response measures, no single polarity and a single electrode are found common. However, with a slight compromise over the machining measures negative tool polarity and copper electrode served the purpose of set objectives (minimum of D.E, TLR, and SR). The expanse of compromise is found to be ≤ 50 µm in axial and radial dimensional errors, 0.8 µm in surface roughness and no compromise in tool length reduction if the copper electrode is assigned with negative polarity.

Purpose Human aging is becoming a common issue these days as it results in orthopaedic-related issues such as joints disorderness, bone-fracture. People with age = 60 years suffer more from these aforesaid issues. It is expected that these issues in human beings will ultimately reach 2.1 billion by 2050 worldwide. Furthermore, the increase in traffic accidents in young people throughout the world has significantly emerged the need for artificial implants. Their implantation can act as a substitute for fractured bones or disordered joints. Therefore, this study aims to focus on electron beam melted titanium (Ti)-based orthopaedic implants along with their recent trends in the field. Design/methodology/approach The main contents of this work include the basic theme and background of the metal-based additive manufacturing, different implant materials specifically Ti alloys and their classification based on crystallographic transus temperature (including α, metastable β, β and α + β phases), details of electron beam melting (EBM) concerning its process physics, various control variables and performance characteristics of EBMed Ti alloys in orthopaedic and orthodontic implants, applications of EBMed Ti alloys in various load-bearing implants, different challenges associated with the EBMed Ti-based implants along with their possible solutions. Recent trends and shortfalls have also been described at the end. Findings EBM is getting significant attention in medical implants because of its minor issues as compared to conventional fabrication practices such as Ti casting and possesses a significant research potential to fabricate various medical implants. The elastic modulus and strength of EBMed ß Ti-alloys such as 24Nb-4Zr-8Sn and Ti-33Nb-4Sn are superior compared to conventional Ti for orthopaedic implants. Beta Ti alloys processed by EBM have near bone elastic modulus (approximately 35–50 GPa) along with improved tribo-mechanical performance involving mechanical strength, wear and corrosion resistance, along with biocompatibility for implants. Originality/value Advances in EBM have opened the gateway Ti alloys in the biomedical field explicitly ß-alloys because of their unique biocompatibility, bioactivity along with improved tribo-mechanical performance. Less significant work is available on the EBM of Ti alloys in orthopaedic and orthodontic implants. This study is directed solely on the EBM of medical Ti alloys in medical sectors to explore their different aspects for future research opportunities.