Design and fabrication of Ti–Zr-Hf-Cr-Mo and Ti–Zr-Hf-Co-Cr-Mo high-entropy alloys as metallic biomaterials

Novel TiZrHfCr0.2Mo and TiZrHfCo0.07Cr0.07Mo high-entropy alloys for metallic biomaterials (bio-HEAs) were developed based on the combination of Ti–Nb–Ta–Zr–Mo alloy system and Co–Cr–Mo alloy system as commercially-used metallic biomaterials. Ti–Zr-Hf-Cr-Mo and Ti–Zr-Hf-Co-Cr-Mo bio-HEAs were designed using (a) a tree-like diagram for alloy development, (b) empirical alloy parameters for solid-solution-phase formation, and (c) thermodynamic calculations focused on solidification. The newly-developed bio-HEAs overcomes the limitation of classical metallic biomaterials by the improvement of (i) mechanical hardness and (ii) biocompatibility all together. The TiZrHfCr0.2Mo and TiZrHfCo0.07Cr0.07Mo bio-HEAs showed superior biocompatibility comparable to that of commercial-purity Ti. The superior biocompatibility, high mechanical hardness and low liquidus temperature for the material processing in TiZrHfCr0.2Mo and TiZrHfCo0.07Cr0.07Mo bio-HEAs compared with the Ti–Nb–Ta–Zr–Mo bio-HEAs gave the authenticity of the application of bio-HEAs for orthopedic implants with multiple functions.Nagase T., Iijima Y., Matsugaki A., et al. Design and fabrication of Ti–Zr-Hf-Cr-Mo and Ti–Zr-Hf-Co-Cr-Mo high-entropy alloys as metallic biomaterials. Materials Science and Engineering C, 107, 110322. https://doi.org/10.1016/j.msec.2019.110322

Distribution of selected trace elements in the major fractions of donkey milk

The aim of this study was to evaluate the concentrations of Zn, Cu, Mn, Se, Mo, Co, Li, B, Ti, Cr, Rb, Sr, Cd, and Pb in donkey milk and their distribution in major milk fractions (i.e., fat, casein, whey proteins, and aqueous phase). Individual milk samples were provided by 16 clinically healthy lactating donkeys. Subsequent centrifugation, ultracentrifugation, and ultrafiltration were carried out to remove fat, casein, and whey proteins to obtain skim milk, a supernatant whey fraction, and the aqueous phase of milk, respectively. Concentrations of the elements were measured in whole milk and fractions by inductively coupled plasma-mass spectrometry, and the concentrations associated with fat, casein, and whey proteins were then calculated. The effect of removal of fat, casein, and whey proteins was determined by repeated-measures ANOVA. The fat fraction of donkey milk carried a small (∼4.5% to 13.5%) but significant proportion of Mo, Co, Ti, Cr, and Sr. The casein fraction in donkey milk carried almost all milk Zn, a majority of Cu and Mn, and most of Mo, Ti, and Sr. Relevant proportions, between 20% and 36%, of Se, Co, and Cr were also associated with caseins. The majority of Se, Co, Li, B, Cr, and Rb, and relevant proportions of Mn, Mo, Ti, and Sr were found in soluble form (ultracentrifuged samples) and distributed between whey proteins and the aqueous phase of milk (ultrafiltered samples). Whey proteins in donkey milk carried the majority of milk Se and Co. All Li and B was present in the aqueous phase of milk, which also contained most Rb and Cr, and 17% to 42% of Mn, Se, Mo, Co, Ti, and Sr

Sintered silicon carbide molded body and method for its production

Sintered silicon carbide shapes are described. They are produced by using a composition containing an oxide of at least one element chosen from the group: Li, Be, Mg, Si, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, Nb, Mo, Ba, Tc, Ta, W and Th as a supplement to known sintering aids

Influence of cobalt and molybdenum additives on the structure and shape memory parameters of reaction-sintered porous nickel titanium alloys

We have studied the structure and properties of porous nickel titanium (TiNi) alloys obtained upon reaction sintering of Ti and Ni powders with Co and Mo additives. It is established that Co and Mo doping additives retain the compaction of Ni powder achieved at the initial stage of sintering. The maximum deformation of porous samples loaded in the austenite state was observed upon adding Co, while the addition of Mo resulted in minimum deformation. The addition of Co leads to single-stage martensitic transformation in TiNi phase, while the addition of Mo leads to the two-stage transformation that is more homogeneous over the volume. Both Co and Mo additives lead to increase in the maximum accumulated strain due to the formation of favorably oriented stress-induced martensite and reoriented quench-induced martensite

Heterodinuclear TiMo and TiW complexes bridged by the (dimethylsilanediyl) dicyclopentadienyl ligand

Reactions of the tricarbonyl-molybdenum and -tungsten complexes [M(CO)3(MeCN)3] (M = Mo, W or [Mo(CO)3(mesitylene)] with equimolar amounts of [Ti(η5-Cp′){(η5-C5H3)(SiMe2)2 (C5H4)}Cl2] (Cp′ = C5H5, C5Me5) lead to the heterodinuclear compounds [Ti(η5-Cp′)Cl2{μ-[(SiMe2)2(η5-C5H3)2]}MH(CO)3]. These dinuclear complexes are isolated as single cis- and trans-isomers or as mixtures of both depending on the starting complex and the reaction conditions. The molar ratio of the two resulting isomers is controlled by thermodynamic and kinetic factors which prevent the application of stereoselective methods for some of the products. Reaction of the hydrido cis- and trans-complexes with CCl4 in CH2Cl2 allows the isolation of chloro complexes [Ti(η5-Cp′)Cl2{μ-[(SiMe2)2(η5-C5H3)2]} MCl(CO)3] of the same configuration. All of the new heterodinuclear compounds reported were characterized by their analytical composition, IR and NMR spectroscopy and the molecular structure of cis-[Ti(η5-C5Me5)Cl2{μ-[(SiMe2)2(η5-C5H3)2]}WH(CO)3] was studied by X-ray diffraction methods.Comunidad Autónoma de Madri

The Design and Research of a New Low Cobalt-molybdenum Niobium-containing Ni-base Superalloy for 700 ̊C Advanced Ultra-supercritical Power Plants

AbstractA new Ni-base Nb-containing supealloy of low Co-Mo, Ni-24Cr-16(Co+Mo+W)-4.5(Nb+Ti+Al)-0.03C (wt. %), was designed for 700°C advanced ultra-super-critical power plant application, and the boiler superheater/reheater tubes were successfully manufactured. The alloy design was conducted by thermodynamics and dynamics calculation using Thermal-Calc and JmatPro commercial software. The microstructural stability of the new alloy was evaluated by FESEM and TEM. The mechanical properties, such as microhardness and impact toughness at room temperature, were also tested. The calculation results show that molybdenum promotes the formation of σ and μ phase obviously and cobalt promotes the formation of η, σ, and μ simultaneously. In addition, high molybdenum content will decrease the flue gas ash corrosion resistance and cobalt is a kind of strategic resource in the world. Therefore, the concept of “low Co-Mo Ni-base superalloy” was determined. The implementation of “Low Co-Mo” can reduce cost, restrain the formation of harmful phases as well as ensure good oxidation/corrosion resistance on the basis of high Cr content. To optimize the new alloy, both the combined solid solution strengthening of Cr-Co-Mo-W and the precipitation strengthening elements Nb, Ti and Al are adopted, because Nb is a good γ’-strengthening element in combination with Ti and Al for Ni-base superalloy. The experimental results of SEM and TEM show that no harmful phases precipitate after 1000 h-aging at 760°C and 800°C, and the γ′ coarsening rate is low, which reveals a good microstructure stability of this new alloy

Types of geochemical associations in the Borov Dol - Shopur area interpretation of the data of primary and secondary haloes

The paper presents statistical calculations of the results of geochemical investigations of the primary and secondary dispersion haloes carried out on an area of some 40 km^2 in the Borov Dol - Shopur region (the Buchim ore district). Sampling was carried out on 500 x 200 spacing by research workers from IMGRE Moscow and the Buchim mine. The results obtained were first interpreted by the Geoscan method and the cluster analysis method (discussed in this paper), as well as the factor analysis of Kaiser method. Based on complex statistical calculations, correlation dependencies and classification of individual elements according to variogramas, factor distributions and dendograms, the types and geochemical associations distinguished are grouped us tollows: 1. Based on cluster analysis the following were distinguished: a) according to primary dispersion haloes (Pb, Zn, Sn). [(Ga, Ag) Vb]. (Ni, Co, Cr), [(Ti, Zr, Y) Nb]; b) according to secondary dispersion haloes [(Ni, Cr, Co) Mn]; [(Ti, V) Sc]; [(Vb, Nb) Ag]; (W, Ga); (Cu, Y) Mo; (Pb, Zn, Sn); 2. Based on data of factor analysis the following were distinguished: a) according to primary haloes [(Zr, Y. B, Ti) Nb]; (Sr); (Pb, Zn, Sn); (Ga, Ag, Vb); (B, Mn, Ni) Co, Cr b) according to secondary haloes: [(Ni, Cr. Co) Mn]; [(Vb, W, Nb) Ag, Ga)J; [(Ti, V) Sc)]; (Pb, Zn, Sn); (Cu, Y, Mo). Particular mention should be made of the (Pb, Zn, Sn) geochemical association which is clearly defined in both groups as well as (Cu, Y, Mo) as n characteristic association for the secondary dispersion haloes

Effects of alloying on aging and hardening processes of steel with 20% nickel

Measurements of hardness, thermal emf, and electrical resistance were used to study the effects of Co, Mo, Ti and Al contents on aging and hardening processes in Fe 20%Ni steel. It is shown that the effects of these alloying elements differ substantially. Anomalies which arise in the temperature dependence of physical properties due to the presence of cobalt and molybdenum are reduced by the inclusion of titanium and aluminum (and vice versa)