Abstract Structure of metallic glasses fascinates as the generic amorphous structural template for ubiquitous systems. Its specification necessitates determination of the complete hierarchical structure, starting from short-range-order (SRO) → medium-range-order (MRO) → bulk structure and free volume (FV) distribution. This link has largely remained elusive since previous investigations adopted one-technique-at-a-time approach, focusing on limited aspects of any one domain. Reconstruction of structure from experimental data inversion is non-unique for many of these techniques. As a result, complete and precise structural understanding of glass has not emerged yet. In this work, we demonstrate the first experimental pathway for reconstruction of the integrated structure, for Zr67Ni33 and Zr52Ti6Al10Cu18Ni14 glasses. Our strategy engages diverse (7) multi-scale techniques [XAFS, 3D-APT, ABED/NBED, FEM, XRD, PAS, FHREM] on the same glass. This strategy complemented mutual limitations of techniques and corroborated common parameters to generate complete, self-consistent and precise parameters. Further, MRO domain size and inter-void separation were correlated to identify the presence of FV at MRO boundaries. This enabled the first experimental reconstruction of hierarchical subset: SRO → MRO → FV→ bulk structure. The first ever image of intermediate region between MRO domains emerged from this link. We clarify that determination of all subsets is not our objective; the essence and novelty of this work lies in directing the pathway towards finite solution, in the most logical and unambiguous way.

The accurate calculation of vibration frequency is essential in design of circular quartz crystal resonators which are the core elements of high-precision microbalances used for testing and measurement. Currently, the prediction of thermal effects on frequency through an analytical analysis is still in its developmental stage, mainly due to the complexity of solving the 3-D equations with the consideration of asymmetric structure of resonators and electrodes along with material anisotropy. By using a scalar differential equation for vibrations with the eigen-displacement of thickness mode, the eigen-frequency of a plano-convex AT-cut circular quartz crystal plate with asymmetric electrodes is determined. Furthermore, the temperature effect in the scalar differential equation is successfully obtained by incorporating the incremental thermal field theory into the 1-D analysis. The theoretical results agree well with the experimental data. The combination of the thermal field and the thickness model for circular quartz crystal resonators can realize a full analysis of thermal properties in vital applications such as high-sensitivity microbalance sensors.

High-speed machining of austenitic stainless steel normally causes significant tool damage and generates reduced tool life. In this paper, five AlTiN PVD coatings with different Al/Ti atomic ratios (50/50, 60/40, 67/33, 70/30 and 73/27) which deposited on cemented carbide inserts were used to conduct high-speed of 370 m/min finish turning tests. The experiments were carried out under different cooling conditions (dry and wet) on SS304 to study the tribological behavior of the AlTiN coatings with different Al/Ti ratios and the effect of the coolant under such aggressive cutting conditions. During the experiments, tool life, cutting force, wear mechanism, friction condition and surface integrity of machined workpiece were investigated. Crater wear was found to be the predominant wear mode during the cutting test, while the complex combination of oxidation, abrasion/attrition, adhesion, and chipping contributed to the tool failure. Given the machining conditions proposed in this study, the results revealed that all coated inserts possessed an improved friction behavior in the wet cutting condition. Compared to the dry machining, all five coatings had exhibited 2–3 times longer tool life. The AlTiN coated insert (Al/Ti = 60/40), in particular, exhibited a cutting length of almost 7000 m, compared to 1000 m for the AlTiN coated insert (Al/Ti = 73/27).

In this study, a novel bi-layer AlTiN PVD coating was deposited on a tungsten carbide substrate. The bi-layer coating, with a total thickness of 3.5 μm consists of a 1.0 μm Al60Ti40N top layer and a 2.5 μm Al50Ti50N sublayer. Monolayer Al60Ti40N and Al50Ti50N coatings (each around 3.5 μm) were used as benchmarks. All the studied coatings were deposited by an industrial cathodic arc PVD coater. The ultra-high-speed finish turning of austenitic stainless steel 304 (SS304) was performed under a cutting speed of 420 m/min. The coatings' mechanical properties (hardness, elastic modulus, toughness, and adhesion) were evaluated using nano-indentation and scratch methods. The obtained data illustrated the influence of the mechanical properties of the coatings on tool wear performance. Cutting tests showed that the longest tool life was achieved by the bi-layer coated tool. Wear morphology studies had revealed that a combination of oxidation/diffusion wear mechanisms resulted in cratering whereas abrasion/attrition led to flank wear. An investigation of tribological characteristics had shown that the bi-layer coated tool produced improved chips. This indicates an optimal frictional condition at the cutting zone. Finally, a chip cross-section analysis was performed to verify the microstructure variations and work-hardening effect in the chips.

Abstract The microstructure and the residual stress state have a significant influence on the service life of the component. The deep rolling process already enables a significant increase in the strength and service life of highly stressed components. By using the hybrid manufacturing process of turn rolling, the edge zone properties can be influenced to such an extent that the service life is further increased compared to conventional deep rolling. In addition to a change in the residual stress state, the use of the turning process temperature also leads to a significant grain refinement in the edge zone area, which has a positive effect on the component service life. This modification of the edge zone can be significantly influenced by the machining speed.

AlTiN coatings with different Al/Ti ratios (50/50, 60/40, 67/33, 70/30 and 73/27) deposited by cathodic arc PVD are investigated in this paper. An ultra-high speed of 420 m/min was applied during the finish turning tests of stainless steel 304 (SS304). The coating structure was characterized by SEM and XRD techniques. Assorted mechanical properties such as elastic modulus, coating adhesion, hardness and micro-scratch fracture toughness were assessed using nano-indentation and scratch testing. Chip characterization was performed to evaluate the tribological characteristics of the tool/chip interface. The wear performance study showed that cratering was the main wear mechanism. Tool life results have shown that the Al60Ti40 coating featured the longest tool life due to its favorable combination of tribological and micro-mechanical properties.

In this paper a new end mill flute design is described which aids in chip formation and management. This new feature, referred to as a chip gash, exists on the flute face and controls the contact area between the forming chip and tool by creating alternating raised or relieved surfaces. The result of this enhancement is reduced specific cutting energy through a reduction in friction. This is shown and discussed through machining tests and FEA simulations. Additionally, it is discussed how these geometry modifications affect chip formation.

With a quartz crystal resonator as the core element, the quartz crystal microbalance (QCM) has been an important sensor for various samples including chemical, biomedical, gas, and liquid with broad applications. The sensing mechanism of QCM is based on the gravimetric effect of samples on vibration frequency of the quartz crystal blank. For accuracy and sensitivity, it is important to have a better estimation of the vibration frequency with the consideration of quartz crystal material, configuration, electrodes, mounting, absorption layer, among other factors. As a result, a thorough study of vibrations of the quartz crystal plate is vital for a good design of the QCM and fabrication processing.

TiB2 is well established as a superhard coating with a high melting point and a low coefficient of friction. The brittle nature of borides means they cannot be utilised with arc evaporation, which is commonly used for the synthesis of hard coatings as it provides a high deposition rate, fully ionised plasma and good adhesion. In this work, TiB2 conical cathodes with non-standard sintering additives (carbon and TiSi2) were produced, and the properties of the base material, such as grain structure, hardness, electrical resistivity and composition, were compared to those of monolithic TiB2. The dependence of the produced cathodes’ electrical resistivity on temperature was evaluated in a furnace with an argon atmosphere. Their arc–evaporation suitability was assessed in terms of arc mobility and stability by visual inspection and by measurements of plasma electrical potential. In addition, shaping the cathode into a cone allowed investigation of the influence of an axial magnetic field on the arc spot. The produced cathodes have a bulk hardness of 23–24 GPa. It has been found that adding 1 wt% of C ensured exceptional arc-spot stability and mobility, and requires lower arc current compared to monolithic TiB2. However, poor cathode utilization has been achieved due to the steady generation of cathode flakes. The TiB2 cathode containing 5 wt% of TiSi2 provided the best balance between arc-spot behaviour and cathode utilisation. Preventing cathode overheating has been identified as a main factor to allow high deposition rate (±1.2 µm/h) from TiB2-C and TiB2-TiSi2 cathodes.