In this study, the mechanical, antibacterial properties and cell toxicity response of Ti-5Al2.5Fe alloy with different copper contents were investigated. The alloys were prepared by high-energy ball milling using elemental Ti, Al, Fe, and Cu powders and consolidated by a uniaxial vacuum hot press. Staphylococcus aureus strain ATCC 29213 and Escherichia coli strain ATCC 25922 were used to determine the antibacterial properties of the sintered alloys. The in vitro cytotoxicity of the samples was evaluated with HeLa (ATTC, CCL-2) cells using thiazolyl blue tetrazolium bromide. The mechanical behavior of the samples was determined as a function of hardness and bending tests and analyzed by scanning electron microscopy, energy dispersive x-ray spectroscopy, optical microscopy and x-ray diffraction (XRD). The results showed that the Cu content significantly improved the antibacterial properties. Cu addition prevented the formation of E. coli and S. aureus colonies on the surface of the samples. All samples exhibited very good cell biocompatibility. The alloys with different copper contents showed different mechanical properties, and the results were correlated by microstructural and XRD analyses in detail. Our results showed that Cu has a great effect on the Ti5Al2.5Fe alloy and the alloy is suitable for biomedical applications with enhanced antibacterial activity.

Ti5Al2.5Fe alloys were fabricated by the spark plasma sintering (SPS) and hot pressing (HP) pressure-assisted sintering techniques from pre-alloyed powders with a particle size of about 200 μm. The powders were sintered at 850 °C for two different holding times (5 and 8 min) and heating rates (50 and 150°C min −1 ) at 25 MPa. The maximum relative densities were 99.70 and 98.78% for SPS and HP samples, respectively. All the alloys prepared by the SPS process had significantly higher bending strengths (1825-2074 MPa) than the alloys prepared by the HP process (648-1330 MPa). A decrease in the heating rate from 150 to 50°C min −1 enhanced the wear resistance of the Ti5Al2.5Fe alloys prepared by both the SPS and HP processes.

In this study, copper alloy matrix composites reinforced with tungsten carbide (WC) particles with the addition of different Ni contents (0, 3, 5, 7, and 10 wt.%) were prepared by the spontaneous infiltration process. Image analysis was used to quantify the microstructural parameters, such as the particle size and distribution, area fraction, binder mean free path, and pore size. The effect of Ni addition on the microstructure, density and hardness are discussed. The results show that a small addition of Ni improves the densification of the infiltrated composites. The highest density value of 11.84 g/cm 3 with a hardness of 327 HV was obtained for the infiltrated composite with the addition of 3 wt.% of Ni. The quantitative analysis results are in good agreement with the microstructure properties and hardness results.

Compositional effects on the dry sliding wear resistance of micrometer-grained WC-10 wt.%(Co +Fe+Ni) cemented carbides pressureless sintered with 2 wt.% Ni but different Fe/Co ratios were investigated. Their microstructures are very similar except for the contiguity of the WC grains, which increased with increasing Fe/Co ratio. Also, these cemented carbides are all almost fully dense, but with the degree of residual porosity exhibiting a complex trend with increasing Fe/Co ratio (first decreasing and then increasing). The greatest densification was reached for an Fe/Co ratio of 1. The reverse trend was observed for the hardness, which reached HV 10 =1090 kg/mm 2 for Fe/Co = 1, indicative that it is dictated essentially by the porosity. The wear resistance correlated inversely with the porosity (and thus directly with the hardness), so that the densest (and thus the hardest) of these cemented carbides (the one sintered with a Fe/Co ratio of 1) also exhibited the lowest coefficients of friction, the lowest specific wear rates, and the lowest microstructural damage. The wear mode was abrasion, with the wear mechanism being plastic deformation and especially fracture. Thus, optimization of the wear resistance of WC-(Co+Fe+Ni) cemented carbides for tribological applications is feasible by a judicious design of their binder composition.

In the current research, the effect of Ag on the mechanical properties of Ti5Al2.5Fe alloy was investigated. The Ti5Al2.5Fe alloy, with different amounts of Ag ranged from 1 to 5 wt. % was prepared by mechanical mixing and then fabricated by hot pressing at 950?C for 15 min under 50 MPa. Three holding steps were applied to the powder compacts to restrain the liquid phases inside graphite die before reaching the maximum sintering temperature. The sintered samples were subjected to hardness, bending and wear tests to study the effect Ag on the mechanical properties of Ti5Al2.5Fe alloy. The microstructural characterization was carried out by means of optical and scanning electron microscope. The results showed that Ag played a differential role on the mechanical properties supported by microstructural constituents. The bending strength and hardness of the produced samples increased with the addition of Ag, the hardness of the alloys then tended to decrease with increasing Ag content but still remained above the hardness of Ti5Al2.5Fe alloy. Wear test also showed similar trends with hardness test results. Finally, the optimum Ag content for the Ti5Al2.5Fe alloy was determined as 1 wt.%. XRD analysis showed that undissolved Ag content was the main reason for the decrease in the mechanical properties.