Improved in-vitro biocompatibility of LZ91 Mg–Li alloy by formation of nanostructured Ti coating through surface mechanical nano-alloying treatment

Surface mechanical nano-alloying treatment (SMNAT) was employed to fabricate a nanostructured Ti coating on LZ91 Mg–Li alloy. Microstructure, surface hardness and in-vitro biocompatibility of the Ti-coated sample were investigated in comparison with those of an untreated sample. Experimental results showed that a nanostructured Ti coating with a thickness of 35 to 60 μm was formed after SMNAT for 2 h. The average grain size in the top surface of the Ti coating was about 30 nm. The surface of the Ti coating is rougher than that of the untreated LZ91 sample, in which the values of Ra, Rq and Rz were 7.83, 9.57 and 14.85 μm, respectively. The hardness of the Ti coating top surface was about 483 HV. Cell proliferation and differentiation on Ti coated samples were enhanced relative to those on the untreated samples.

Calcium substituted with magnesium, silver and zinc in hydroxyapatite: a review

Hydroxyapatite with the chemical formula Ca10(-PO4)6(OH)2 is an important bioceramic well known for its high osteoconductive properties, non-toxic nature, high bioactivity and good biocompatibility. Moreover, it is known to mimic natural bone. Inspite of the above mentioned advantages, it has certain disadvantages such as having poor mechanical properties, being brittle, not showing an inhibitory effect on microbes and taking a long time to resorb in the body. These disadvantages can be covered up by the addition of dopants which include cations, anions and polymers. These are sufficiently known to improve the properties of hydroxyapatite. This review focuses on the substitution of hydroxyapatite with silver, zinc, magnesium ions and alloys to show the changes in the morphology and biocompatible properties of hydroxyapatite after substitution of the ions in the matrix.

Parametric optimization of friction stir processing on micro-hardness of Al/B4C composite

Friction stir processing was used to prepare aluminium metal matrix composite reinforced with B4C particles. The micro-hardness of the composite was improved by selecting the process parameters. Friction stir processing parameters, namely tool rotational speed, tool tilt angle and different pin profiles, were explored by using Taguchi’s L9 orthogonal array and analysis of variance. Optical microscopy and scanning electron microscopy were employed for microstructural analysis. X-ray diffraction was used to evaluate the residual stress. Experimental results illustrated that increased rotational speed, reduced tilt angle and square pin profile of the tool gave more uniform dispersal of B4C content with maximum micro-hardness. Small amounts of compressive residual stress developed at the stirred and thermo-mechanically affected zones confirmed the adequate improvement in micro-hardness. Micro-hardness of fabricated Al 6063/B4C composite surfaces was enhanced by 30% as compared to Al 6063 alloy.

Effects of carbon doping on structure and magnetocaloric properties of Mn1.25Fe0.7P0.5Si0.5 alloys

(Mn,Fe)2(P,Si)-basedmaterials are promisingly applied in the room-temperature magnetic refrigeration field. In this study, Mn1.25Fe0.7P0.5Si0.5Cx (x = 0, 0.01, 0.03 and 0.05) alloys were prepared by arc-melting and then a two-stage sintering process. The effects of C doping on the crystal structure and magnetocaloric behavior are discussed. Results indicate that the Fe2P-type structure (space group of P62 m) was crystallized for all samples with weakened first-order magnetic transitions (FOMT). The Curie temperature could be altered from 223.5 K to 278.5 K with the large magnetocaloric effect (MCE) remaining by C doping. In the applied magnetic field of 5 T, the peak value of magnetic entropy change (–ΔS M) increased by 7.3% to reach 25.1 J × kg–1 × K–1. The temperature-induced entropy change (ΔS DSC) derived from DSC was slightly larger than ΔS M induced by the magnetic field. The Mn1.25Fe0.7P0.5Si0.5 alloys with large MCE can be effectively tuned by C doping because C atoms prefered to share the substitute and occupy the interstitial sites in hexagonal Fe2P-type structure.

Composition design, microstructure, and mechanical properties of novel Ti–Co–Ni–Zr complex concentrated alloys

The composition design of complex concentrated alloys originates from the composition design of amorphous alloys. To expand the composition design of alloys, herein, the compositions of novel Ti–Co–Ni–Zr complex concentrated alloys were obtained by the proportional mixing of Ti2Co intermetallics and Ni64Zr36 binary eutectic. The theory and method of this new alloy design are also discussed. The as-cast Ti28Co14Ni37.12Zr20.88, Ti30Co15Ni35.2Zr19.8, and Ti32 . Co16Ni33.3Zr18.7 alloys were composed of body-centered cubic TiNi and Ti2Ni phases. The Ti28Co14Ni37.12Zr20.88 alloy exhibited high yield strength (2 164 MPa) and compressive strength (2 539 MPa) under quasi-static compression at roomtemperature. The high strength of Ti28Co14Ni37.12Zr20.88 alloy is related to the precipitation of Ti2Ni along the grain boundary and the precipitation in the crystal. This paper validates that using the proportional mixing method of intermetallics and eutectic alloy is an effective method to design complex concentrated alloys with high strength.

Supercapacitor electrodes based on modified titania nanotube arrays on flexible substrates

Highly ordered titania nanotube arrays were synthesised on titanium metal foil through electrochemical anodisation. The annealed samples were characterised through scanning electron microscopy and X-ray diffraction analysis. The electrochemical characterisations of the arrays were done through cyclic voltammetry, galvanostatic charge discharge and electrochemical impedance spectroscopy analyses. The titania nanotube arrays exhibited a specific capacitance of 6.8 mF cm–2 at 5 mV s–1 scan rate, which is very much higher than that reported earlier. Pseudocapacitive metal oxides were deposited on these arrays forming composite supercapacitor electrodes and their supercapacitor properties were compared with same deposited on bare titanium foil substrates. Pseudocapacitive metal oxides deposited on these titania nanotube array substrates exhibited improved supercapacitor performance and stability over the same deposited on titanium foil substrates.

The effect of V on the morphology of TiB2 particles in as-cast aluminum composites

This study presents the modification effect of trace vanadium on the in-situ formed TiB2 particles in as-cast aluminum composites. With 0.2 wt.% V addition the morphology of TiB2 was modified from hexagonal platelet or irregular feather-like shape to hexagonal prism or rectangular prism with parallel growth steps along the c-axis. Meanwhile, V rich cores were detected in the center of TiB2 and the exposure of the high-index crystal plane (1101)TiB2 was detected in Al-0.2 wt.%V. Statistical analysis of the particle size and aspect distribution both in commercial Al and Al-0.2 wt.%V was conducted. The elemental distribution and scanning electron microscopy investigation revealed that VB2 may serve as the 2D-nucleus of TiB2 particles. The growth mechanism of TiB2 under the influence of V was explored.

A solid-state approach for the low temperature synthesis of Cr3Si hollow particles

In this paper, pure cubic chromium silicide (Cr3Si) hollow particles have been successfully synthesized through the solid-state reaction of chromium sesquioxide, silicon powder and metallic lithium in an autoclave at 600 °C for 10 h. The as-prepared samples were characterized by means of X-ray diffraction, field emission scanning electron microscopy and transmission electron microscopy, which showed that the as-prepared samples were cubic phase Cr3Si hollow particles. Furthermore, the oxidation resistance of the obtained Cr3Si sample was also investigated.