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Titanium and its alloys have been used extensively in the last few decades as materials for orthopedic and dental implants and other medical devices due to their high strength, low modulus, and high corrosion resistance in biological media. Besides other important material features, the corrosion parameters and corrosion products are responsible for limiting the biocompatibility of metallic materials, and can produce undesirable reactions in implant-adjacent and/or more distant tissues. Electrochemical corrosion behaviors of novel beta titanium alloys, Ti-4.7 Mo-4.5 Fe, Ti-3Mo-0.5 Fe and Ti-2Mo-0.5 Fe were investigated in naturally aerated Ringer’s solution at room temperature compared with currently used biomedical titanium alloy, Ti-6Al-4V. Very low current densities were obtained from the potentiodynamic polarization curves, indicating a passive behavior for all the studied alloys. Electrochemical impedance spectroscopic (EIS) studies showed high impedance values for all samples indicating an improvement in corrosion resistance of the spontaneous oxide layer. The fitting data obtained suggests a single passive layer form on the virgin surfaces of the alloys. The EIS results exhibited capacitive behavior (high corrosion resistance) with phase angles close to-80 C and high impedance values at low and medium frequencies, which are indicative of the formation of a highly stable film on these alloys in the test solution. The new present alloys are promising metallic biomaterials for the future, owing to their very low elastic modulus and good corrosion resistance capabilities.

Recently, researchers has given attention to the low‐cost Ti‐alloys with low Young's modulus for biomedical applications. This can be done by substituting partially or totally the expensive rare metals with the common low‐cost elements. In such a way, the low‐cost Ti‐2Mo‐0.0∼2.0 Fe alloy system is studied. The elastic modulus of the Ti‐2.0Mo alloys containing 0.0∼1.0 Fe is of low value of approximately 80∼85GPa where the a'‐ and a"‐martensite phases are present. In this alloy system, the hardness is relatively high and increases monotonously with increasing the Fe‐content. The corrosion resistance of Ti‐2Mo‐0.5Fe alloy is higher than Ti‐6Al‐4V alloy. The cell viability is also very high (above 100%). Among the studied alloys, Ti‐2.0Mo‐0.5Fe alloy seems to be a candidate alloy for low‐cost bone replacement materials with low Young's modulus and to replace the commercial Ti‐6Al‐4V alloy.

In this work, two new α + β titanium alloys with low contents of ubiquitous and low-cost alloying elements (i.e., Mo and Fe) were designed on the basis of the electronic parameters and molybdenum equivalent approaches. The designed Ti – 2Mo – 0.5Fe at. % (TMF6) and Ti – 3Mo – 0.5Fe at. % (TMF8) alloys were produced using arc melting process for studying their mechanical, electrochemical and cytotoxicity compatibilities and comparing these compatibilities to those of Ti-6Al-4V ELI alloy. The cost of the used raw materials for producing the TMF6 and TMF8 alloys are almost 1/6 of those for producing the Ti-6Al-4V ELI alloy. The hardness of the two alloys are higher than that of the Ti-6Al-4V ELI alloy, while their Young's moduli (in the range of 85–82 GPa) are lower than that of the Ti-6Al-4V ELI alloy (110 GPa). Increasing the Mo equivalent from 6 (in TMF6 alloy) to 8 (in TMF8 alloy) led to an increase in the plastic strain percent from 4% to 17%, respectively, and a decrease in the ultimate tensile strength from 949 MPa to 800 MPa, respectively. The microstructure of TMF6 alloy consists of α′/α″ phases, while TMF8 alloy substantially consists of α″ phase. The corrosion current densities and the film resistances of the new alloys are in the range of 0.70–1.07 nA/cm2 and on the order of 105 Ω·cm2, respectively. These values are more compatible with biomedical applications than those measured for the Ti-6Al-4V ELI alloy. Furthermore, the cell viabilities of the TMF6 and TMF8 alloys indicate their improved compatibility compared to that of the Ti-6Al-4V ELI alloy. The CCK-8 (Cell Counting Kit-8) assay was conducted to investigate the cytotoxicity, proliferation, and shape index of the cells of the candidate alloys. Overall, the measured compatibility of the new V-free low-cost alloys, particularly TMF8, makes them promising candidates for replacing the Ti-6Al-4V ELI alloy in biomedical applications.

Purpose This paper aims to clarify the relationship between the slurry erosion and one of the case hardening treatments, i.e. boronizing in this study, for AISI-5117 steel alloy. AISI-5117 steel alloy was used because of its variety applications in the field of submarine equipment. Most of the slurry erosion factors such as velocity, impact angle and mechanism of erosion were studied at different impact angles. Design/methodology/approach At first, the samples were prepared and subjected to the boronizing treatment in controlled atmosphere. By using a slurry erosion test-rig, all experiments for studying the slurry erosion factors were carried out. Moreover, the studied specimens were investigated via scanning electron microscope, optical microscope and X-ray diffraction to study the erosion mechanism in the different conditions. Findings It was expected that the boronization of the AISI-5117 steel would increase its slurry erosion resistance due to its positive impact on the surface hardness. However, the results observed show the opposite, where the boronization of AISI-5117 steel decreased its slurry erosion resistance as implied by the increase of the mass loss percentage at all impact angles. Originality/value This research, for the first time, exhibits the effect of boronizing treatment on the slurry erosion in different impact factors accompanied by the erosion mechanism at each impact angle.

Purpose This paper aims to clarify the relationship between the slurry erosion and one of the case hardening treatments, i.e. boronizing in this study, for AISI-5117 steel alloy. AISI-5117 steel alloy was used because of its variety applications in the field of submarine equipment. Most of the slurry erosion factors such as velocity, impact angle and mechanism of erosion were studied at different impact angles. Design/methodology/approach At first, the samples were prepared and subjected to the boronizing treatment in controlled atmosphere. By using a slurry erosion test-rig, all experiments for studying the slurry erosion factors were carried out. Moreover, the studied specimens were investigated via scanning electron microscope, optical microscope and X-ray diffraction to study the erosion mechanism in the different conditions. Findings It was expected that the boronization of the AISI-5117 steel would increase its slurry erosion resistance due to its positive impact on the surface hardness. However, the results observed show the opposite, where the boronization of AISI-5117 steel decreased its slurry erosion resistance as implied by the increase of the mass loss percentage at all impact angles. Originality/value This research, for the first time, exhibits the effect of boronizing treatment on the slurry erosion in different impact factors accompanied by the erosion mechanism at each impact angle.

Purpose This paper aims to clarify the relationship between the slurry erosion and one of the case hardening treatments, i.e. boronizing in this study, for AISI-5117 steel alloy. AISI-5117 steel alloy was used because of its variety applications in the field of submarine equipment. Most of the slurry erosion factors such as velocity, impact angle and mechanism of erosion were studied at different impact angles. Design/methodology/approach At first, the samples were prepared and subjected to the boronizing treatment in controlled atmosphere. By using a slurry erosion test-rig, all experiments for studying the slurry erosion factors were carried out. Moreover, the studied specimens were investigated via scanning electron microscope, optical microscope and X-ray diffraction to study the erosion mechanism in the different conditions. Findings It was expected that the boronization of the AISI-5117 steel would increase its slurry erosion resistance due to its positive impact on the surface hardness. However, the results observed show the opposite, where the boronization of AISI-5117 steel decreased its slurry erosion resistance as implied by the increase of the mass loss percentage at all impact angles. Originality/value This research, for the first time, exhibits the effect of boronizing treatment on the slurry erosion in different impact factors accompanied by the erosion mechanism at each impact angle.