Microstructural, microhardness and electrochemical properties of heat-treated LENS in-situ synthesized Ti-Al-x(Mo, Si) alloys.

So as to explore the opportunity of property enhancement of TiAl-based alloys, studies of microstructural evolution after processing with heat treatments are to be expected. Therefore, the objective of this present study is to investigate how additions of silicon (Si) and molybdenum (Mo) as alloying elements affects the microstructure, microhardness, corrosion behaviour, and wear properties of Ti-Al-x(Mo, Si) alloys made from constituent elemental powders through in-situ alloying laser engineered net shaping (LENS) technique. The influence of the feed rate of Si powder (0.1 rpm, 0.2 rpm and 0.3 rpm) on Ti-Al-xMo was studied at 0.1 rpm and 0.2 rpm Mo feed rate, respectively. Heat treatment at 1200 °C for 15, 30, and 60 min was performed after LENS in-situ alloying, and furnace cooling (FC) was the final step. The microstructure of the produced alloys was analyzed via Scanning electron microscopy (SEM) fitted with energy dispersive spectroscopy (EDS). Using a tribometer and a potentiodynamic polarization test, the alloys' wear characteristics and corrosion behaviour were studied. Based on the results, it was noticed that microhardness values decrease after heat treatment for all the samples produced. Owing to the combined effects of Mo and Si, both the ßo-TiAl and ζ-Ti5Si3 phases lead to solid precipitation hardening and solution strengthening at the grain boundaries. The XRD analysis confirmed γ, α2, α, ßo and ζ-Ti5Si3 phases occurrence in the as-built alloys. The LENS fabricated alloys demonstrated improved wear properties and marginally change in corrosion behavior after heat treatment.

Synthesis of Ti-Al-xNb Ternary Alloys via Laser-Engineered Net Shaping for Biomedical Application: Densification, Electrochemical and Mechanical Properties Studies.

The lives of many people around the world are impaired and shortened mostly by cardiovascular diseases (CVD). Despite the fact that medical interventions and surgical heart transplants may improve the lives of patients suffering from cardiovascular disease, the cost of treatments and securing a perfect donor are aspects that compel patients to consider cheaper and less invasive therapies. The use of synthetic biomaterials such as titanium-based implants are an alternative for cardiac repair and regeneration. In this work, an in situ development of Ti-Al-xNb alloys were synthesized via laser additive manufacturing for biomedical application. The effect of Nb composition on Ti-Al was investigated. The microstructural evolution was characterized using a scanning electron microscope (SEM) equipped with energy dispersive spectroscopy (EDS). A potentiodynamic polarization technique was utilized to investigate the corrosion behavior of TiAl-Nb in 3.5% NaCl. The microhardness and corrosion behaviour of the synthesized Ti-Al-Nb alloys were found to be dependent on laser-processing parameters. The microhardness performance of the samples increased with an increase in the Nb feed rate to the Ti-Al alloy system. Maximum microhardness of 699.8 HVN was evident at 0.061 g/min while at 0.041 g/min the microhardness was 515.8 HVN at Nb gas carrier of 1L/min, respectively.

Characteristic effects of alloying elements on ß solidifying titanium aluminides: A review.

The high strength-to-weight ratio property of titanium aluminide (TiAl) based intermetallic alloys makes researchers regard this type of material as a potential replacement for the heavier superalloys of nickel. These alloys have been applied as turbocharger wheels of automobile and turbine blades of aircraft engines. A much recent alloy type of TiAl called the TNM alloy has emerged and primarily amenable to mechanical working; while providing the best combinations of mechanical properties that could be achieved through manufacturing processes with subsequent heat treatments. This is attained by solidifying entirely through the disordered ß-phase (A2 structure). Effects of major alloying elements such as strength improvement, microstructural stability and phase formation demand the understanding of these alloying elements addition in TiAl-based intermetallic alloys. This review paper aims at encapsulating several works regarding the effects of major alloying elements on ß-solidifying TiAl-based alloys and summarizing the characteristic effects of Si for these types of alloys. An impetus for future works on these types of intermetallic TiAl-based alloys is also presented.

Bioremediation: Data on Pseudomonas aeruginosa effects on the bioremediation of crude oil polluted soil.

This data article details Pseudomonas aeruginosa effects on the bioremediation of soil that had been polluted by different concentrations, 5% w/w and 8% w/w, of raw (for simulating oil spills from well-heads) and treated (for simulating oil spills from flow lines/storage tanks) crude oil. UV/VIS spectrophotometry instrumentation was used for obtaining absorbance measurements from the Nigerian Escravos Light blend (sourced from Chevron® Nigeria) of crude oil polluting soil samples, which, thus, also simulates light and heavy onshore oil spillage scenarios, in a 30-day measurement design. Data on bioremediation effects of Pseudomonas aeruginosa added to the crude oil polluted soil samples, and which were monitored at intervals via the absorbance measurement techniques, are presented in tables with ensuing analyses for describing and validating the data presented in graphs. Information from the presented data in this article is useful to researchers, the oil industries, oil prospecting communities, governments and stakeholders involved in finding solution approach to the challenges of onshore oil spills. This information can also be used for furthering research on bioremediation kinetics such as biostimulant analyses, polluting hydrocarbon content/degradation detailing, by Pseudomonas aeruginosa strain of microorganism, on petroleum pollutant removal from soil that had been polluted by crude oil spillage.