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Zirconia-toughened alumina (ZTA) ceramics have attracted much attention in the medical field as joint replacement materials due to their good mechanical properties and biocompatibility. However, the flexural strength of conventional ZTA is still slightly insufficient in traditional preparation techniques. In this study, by improving the slurry system, the effects of the solid content of the slurry, additives, and the pH of the slurry on the slurry system were investigated. ZTA powders with a uniform particle size distribution, high degree of sphericity and high flowability were prepared by spray granulation. The mechanical properties, microstructure and biocompatibility of the ZTA pressing were investigated after degreasing and sintering processes. The results showed that the hardness of the prepared ZTA ceramics was 1658.24 ± 28.04 H V, the fracture toughness was 4.016 ± 0.027 MPa m1/2, and the biaxial bending strength was 501.43 ± 21.44 MPa, and the three-point bending strength reached 635 MPa. The ZTA ceramics also possessed good biocompatibility and a low haemolysis rate, which aligns with the requirements of clinical biomedical implant materials. [ABSTRACT FROM AUTHOR]

A novel Ti–2Al–1.3V (wt.%) alloy was prepared by thermomechanical consolidation of a composite powder produced by high-energy ball milling of a mixture of TiH2 granules with a low oxygen content (0.1wt.%) and Ti–6Al–4V machining chips with a high oxygen content (0.8wt.%) at a mass ratio of 2:1. The microstructures and mechanical properties of the alloy in as-extruded state and after different heat treatments were investigated. The as-extruded alloy exhibits a martensite microstructure consisting of ultrafine and nanometer sized α' laths and aciculae and domains of layered structure containing δ(TiH) layers. The alloy in this state is brittle and fractures prematurely before yielding due to the ultrafine martensitic microstructure and hydrogen embrittlement associated with the high hydrogen content of the alloy. After vacuum annealing at 700°C for 6 h followed by furnace cooling, the alloy is further dehydrogenated with the hydrogen content being reduced to 0.008wt.%, the microstructure of the alloy changes into a full α/β lamellar microstructure with the continuous and discontinuous β layers being only 80–90 nm thick and the lamellar colony sizes being 10–30μm. The fine structured alloy in this heat treatment condition shows an excellent combination of high tensile yield strength of 996 MPa and ductility of 13.9%. After a further heat treatment of 980°C for 1 h followed by air cooling, the microstructure of the alloy consists of equiaxed α grains and α/βt lamellar structured domains (βt = β transformed structure), and unfortunately, this microstructure leads to a significant decrease of both the tensile yield strength (to 876 MPa) and the tensile ductility (to 7.4%). The fracture behavior of the alloy in different states is also studied, and the correlation between the microstructure and mechanical properties is discussed. [ABSTRACT FROM AUTHOR]

Aqueous tape calendering offers the advantage of a simple fabrication process, inexpensive equipment, and environmental friendliness. Polyvinyl alcohol (PVA), as a polymer, is a conventional binder for aqueous tape calendering. In this innovative work, we aim to achieve a suitable process for tape calendering, by studying mechanical properties of the PVA polymer film with a series of plasticizers. The results show that the elongation at break of the PVA film reaches a maximum of 828.26%, using a triple plasticizer of glycerol, polyethylene glycol (PEG) 200, and PEG 400. With an optimized ratio of the binder to the plasticizer, a YSZ sheet with a relative density of 98% and a conductivity of 0.043 S cm−1 at 800 °C is obtained by sintering at 1400 °C, demonstrating comparable performance to those of the YSZ electrolytes by dry pressing. SEM reveals that the sintered YSZ body is dense, and has no visible open and closed pores. The mechanical properties characterization of the PVA polymer film adopted in this paper has instructive significant instruction for tape calendering and tape casting methods. • Mechanical properties measurement of the PVA film applied in an aqueous tape calendering. • The elongation at break of the PVA film reached 828%. • Combination of glycerol, PEG200 and PEG 400 plasticizer is a preferred choice for PVA binder. • The YSZ sheet sintered at 1400 °C has a density of more than 98% and a conductivity of 0.043 S cm−1 at 800 °C. [ABSTRACT FROM AUTHOR]

This study aims to evaluate the effects of ZrO 2 types including YSZ and nano-ZrO 2 as well as their contents on the phase compositions, macrostructures, microstructures, physical properties, mechanical properties and biocompatibility of Ti2448-ZrO 2 composites fabricated by spark plasma sintering (SPS). The mechanical properties such as hardness and compressive yield strength of the composites have been systematically investigated. The experimental results demonstrate that the hardness and compressive yield strength of the composites all dramatically increased with increasing the content of YSZ and nano-ZrO 2 . Meanwhile the nano-ZrO 2 could be beneficial to the uniformity of microstructure and improvement in mechanical strength of the composites. The biocompatibility of the composites containing nano-ZrO 2 was found to possess better corrosion resistance. In conclusion, Ti2448-ZrO 2 composites are potentially useful in biomedical applications with their mechanical and biological properties being evaluated in this work. [ABSTRACT FROM AUTHOR]

Powder metallurgy (PM) Ti–6Al–2Sn–4Zr–2Mo–0.1Si–(0, 2, 4)W (wt%) alloys were fabricated by thermomechanical consolidation of TiH 2 -based powder compacts and subsequent heat treatments. Samples of the as-fabricated alloys were also heated at 650 °C for 200 h. The addition of 2 or 4 wt%W to the base alloy changed its microstructure of parallel α/β lamellar colonies and grain boundary α (α GB) to an interwoven α/β t microstructure consisting of α GB and a network of interpenetrating α plates with β transformed structure (β t) domains comprising variants of fine α laths and β matrix. The partition of the β stabilizing W between β and α phases and the low diffusivity of W atoms limited the growth of α plates/laths, decreasing the thickness of α plates/laths and increasing the volume fraction of β. The increased hardening of the β phase and enhanced α/β interface strengthening associated with the 4 wt%W addition led to a significant increase in the tensile strength of the alloy from 1281 ± 10–1411 ± 12 MPa. However, the high flow stress and the very fine microstructure caused significant strain localization in the weak α GB , resulting in premature fracture of the α GB (intergranular fracture) and the low ductility (1.4%). Here, premature fracture meant the fracture occurred prior to the alloy reaching its ultimate tensile strength. The heating caused the β interlaths in the W-free alloy to partially dissolve and become β particles distributed along the original lines of β interlaths accompanied by the precipitation of α 2 -Ti 3 Al in the α plates. The addition of W inhibited the dissolution of β interlaths and caused the precipitation of a higher volume fraction of α 2 precipitates during heating. The microstructural changes caused by heating resulted in a slight decrease in strength and a significant decrease in ductility for the W-free alloy, but a significant increase of the yield strength of the 2 W and 4 W alloys with some sacrifice of the tensile ductility. The microstructural reasons for the effects on mechanical properties were analyzed with the assistance of detailed characterization of the dislocations in the deformed specimens. • Effects of W alloying on a PM Ti–6Al–2Sn–4Zr–2Mo–0.1Si alloy are investigated. • W refines α plates and enhances formation of β transformed structure domains. • W enhances hardening of the β phase and α/β interface strengthening. • W increases the microstructural stability and prevents the strength reduction from heating. • High W content promotes α 2 precipitation strengthening of the alloy after heating. [ABSTRACT FROM AUTHOR]

Two samples of an α + β Ti-4Al-4Mo-4Sn-0.5Si (wt%) alloy, one with fine prior β grains and a heterogeneous microstructure and the other with coarse prior β grains and a homogeneous microstructure were prepared by extrusion of compacts of TiH 2 /Al/Mo/Sn/Si powder blend at 1200 and 1300 °C respectively. The heterogeneous microstructure is manifested by softer Mo-rich regions with a full α/β lamellar structure containing a high number density of parallel and nanometer sized FCC δ (TiH) needles in a harder matrix with a microstructure consisting of interweaved α plates and β transformed structure (β t) domains and grain boundary α (GB α) layers. The matrix also contains a small fraction of Sn-rich regions which have the same microstructure as the matrix. The Mo-rich and Sn-rich regions form due to the limited diffusion of Mo and Sn alloying elements. This heterogeneous microstructure sustains a high tensile yield strength of 1199 MPa, a high strain hardening rate, and an excellent tensile ductility of 12.0%. In contrast, the homogeneous microstructure comprising of interweaved α plates and β t domains together with GB α layers sustains a similar high strength, but a clearly lower strain hardening rate and a significantly lower tensile ductility of 3.5%. Non-homogeneous deformation capacity, the release of energy by forming numerous microcracks and the intermittent growth of microcracks of the heterogeneous microstructure suggest that this microstructure has a high plasticity and high resistance to the growth of microcracks. • The α + β titanium alloy fabricated has a heterogeneous microstructure and fine prior β grains. • The heterogeneous microstructure encompasses softer Mo-rich regions in a matrix of α/β t microstructure. • This alloy exhibits a superior combination of high strength (YS: 1199 MPa and excellent ductility (12.0%). • This is attributed to the compatible deformation and high microcrack growth resistance of the microstructure. [ABSTRACT FROM AUTHOR]

• With an addition of 0.2 wt%Si, the Si atoms are equally in α and β phases. • Si solute atoms retard the growth of α phase, causing refinement of the α/β t lamellar structure. • Si atoms enhance solid solution strengthening and Si atoms enhanced α/β t interface strengthening. • Increasing the Si content to 0.5 wt% cause a further increase of the yield strength by 50 MPa. • With a high strength, the tensile ductility deteriorates, due to the premature fracture of grain boundary α layers. Ti-4Al-4Mo-4Sn-xSi (wt%) (x = 0, 0.2, 0.5) alloys were fabricated by hot extrusion of compacts of blends of TiH 2 , AlMo60 master alloy and other required elemental powders followed by heat treatments involving vacuum annealing, solution treatment, air cooling and aging. The microstructure of the alloys consists of α plates, lamellae of α and transformed β structure (β t), β t blocks as well as grain boundary α layers. With the addition of 0.2 wt%Si, the Si atoms exist in equal concentration in both α and β t regions as solute atoms, and they retard the growth of α phase, causing a decrease of the average thickness of α plates and lamellae and slight increase of the volume fraction of β t lamellae and blocks. The solid solution strengthening and enhanced α/β interface hardening brought by the 0.2 wt%Si cause the yield strength of the Ti-4Al-4Mo-4Sn alloy to increase significantly from 1030 to 1130 MPa with a slight decrease of the tensile ductility (7.4% vs 6.8%) and without changing the fracture behavior. With the addition of 0.5 wt%Si, the extra Si causes nanometer sized silicide (Ti 5 Si 3) precipitates to form in both α and β t regions and further microstructural refinement. The additional α/β interface hardening and precipitation hardening cause the yield strength of the alloy to increase further to 1177 MPa, but the tensile ductility deteriorates clearly with the elongation to fracture decreasing to 4.9%. The main reason for this ductility decrease is the premature fracture of grain boundary α layers caused by the higher flow stress which can induce more strain localization at the grain boundary α layers. [ABSTRACT FROM AUTHOR]

• A numerical simulation model has been developed, and was consistent well with the experimental results. • The strength, modulus and energy absorption capacity of the Pyramidal Kagome lattice material were proportional to the square of its relative density. • The strain rate hardening effect of the base material plays a major role for the rate sensitivity of the Pyramidal Kagome lattice material. • Increasing the number of lateral units and reducing the number of layers contributed to the improvement on the mechanical properties of the Pyramidal Kagome lattice material. The present study aimed at understanding the influences of structural parameters on the mechanical properties of Pyramidal Kagome (PK) lattice material under impact loading. Seven different PK structures varying height-width ratio and rod diameter were manufactured by selective laser melting (SLM). In this study, both experiments and simulation were conducted to understand the influences of rod diameter, height-width ratio, number of unites and layers on the mechanical properties of PK lattice material. The failure characteristics and the deformation process were recorded by using the digital photography technique. All the specimens were observed to have a clear rupture along 45°in the quasi-static test, while broke along the direction of the vertical panel in the SHPB test with a strain rate of about 2000s−1.The results showed that the initial deformation zone of the PK switched from the intermediate layer to the lower and upper layer with the increase of rod diameter. Moreover, the strength, modulus and energy absorption capacity of the PK were proportional to the square of its relative density. As the height-width ratio increases, the modulus of the PK gradually increased. In addition, increasing the number of lateral units and reducing the number of layers contributed to the improvement on the mechanical properties of the PK. [ABSTRACT FROM AUTHOR]

Abstract Two novel diamond lattice structures (Dfcc and Dhex) and the typical face-centered cubic (FCC) and body-centered cubic (BCC) lattice structures are manufactured by selective laser melting (SLM), and the effects of cell topology and relative density on the dynamic behavior of these structures are studied through a combination of experimental tests and numerical simulation. It is observed that in Dfcc and Dhex, failure initiates at the connection points between rods in the middle of the structure, causing a sudden drop of the measured stress value. However in FCC and BCC, failure initiates in the face-truss junction. Generally, the FCC and BCC are dominated by stretching and bending of the rods respectively, whereas the Dfcc and Dhex are a mixture of the two deformation modes. The results show that the mechanical properties of the lattice structures with different relative density can be described by a power law function. Moreover, for the lattice structures with the same rod diameter of 0.8 mm, FCC out-performs other structures in terms of specific strength, specific modulus and energy absorption. This gives evidence that lattice structures with the stretching-dominated deformation mode are more likely to exhibit better mechanical properties under dynamic loading. Graphical abstract Unlabelled Image Highlights • Two novel diamond lattice structures (Dfcc and Dhex) and the typical FCC and BCC lattice structures were designed. • A numerical simulation model has been developed, and was consistent well with the experimental results. • Using a power law function to relate different mechanical properties to rod diameter or relative density for each lattice type. • Stretching-dominated structures often exhibit better dynamic mechanical properties than bending-dominated structures. [ABSTRACT FROM AUTHOR]