Laser cladding is an effective technique to coat a metallic substrate with a layer of a different nature. It has been widely reported that the most important combined parameters controlling the quality of the coating are the specific energy (E) and the powder density (). In the present work, clad deposits of Ti6Al4V+60%wt TiC were prepared on a Ti6Al4V substrate using an optimum combination of E c = 24 J/mm 2 and ψ c = 3 mg/mm 2. These experiments were performed using a laser power of 400 and 600 W, in order to study the effect of laser power on the properties of the clad. The microstructure, phase composition and nanohardness of the coatings were investigated by optical microscope, scanning electron microscopy and X-ray diffraction. During laser processing, TiC can be partially converted to TiC X (X = 0.5) due mainly to the TiC dissolution into the laser-generated melting pool and subsequent precipitation during cooling. It was observed that the lower laser power limit reduces primary TiC dissolution but it also promotes secondary carbide alignment at the interface. On the other hand, the damage mechanism induced by high laser power is dominated by primary TiC particle cracking by the high stress concentration at the particle-matrix interface followed by ductile failure of the matrix. It is also remarkable that irradiance affects the TiC/TiC x ratio despite E c and ψ c are fixed and it determines hardness distribution inside the coating.

Las aleaciones de titanio son ampliamente utilizadas en el sector biomédico para la fabricación de implantes quirúrgicos debido a su gran resistencia a la corrosión, biocompatibilidad y propiedades mecánicas. No obstante, existe un gran interés científico en desarrollar nuevas aleaciones de titanio que presenten menor módulo de elasticidad para evitar el apantallamiento de tensiones [1] .Las aleaciones de titanio basadas en elementos como niobio y tantalio son las que poseen mejores propiedades para este tipo de aplicaciones [1] debido a su bajo módulo elástico, que empieza con valores cercanos a 100 GPa para las alfa más beta y llega a valores inferiores a 60 GPa para las aleaciones beta, así como su excelente biocompatibilidad en general [2] . No obstante, la adición de elementos refractarios en cantidades elevadas como el niobio o tantalio complica la fabricación de estas aleaciones debido a la heterogeneidad en la composición y la implicación que tiene en las transformaciones de fase de la aleación [3] .La pulvimetalurgia del titanio puede ser una alternativa interesante a la fusión en alto vacío ya que permite mayor productividad y la posibilidad de fabricar ResumenEl niobio y el tantalio se añaden al titanio para formar nuevas aleaciones beta con mayor biocompatibilidad para aplicaciones biomédicas. Ambos elementos tienen un elevado punto de fusión, por lo que su difusión en estado sólido es limitada. En este trabajo se han fabricado por pulvimetalurgia muestras de titanio con 3% atómico de niobio o tantalio. Se estudia el efecto de la presión de compactación, la temperatura y el tiempo de sinterizado sobre la resistencia, la elasticidad y la ductilidad a flexión. Los resultados muestran que ambos elementos se comportan de manera semejante: aumenta la resistencia entre 20-25%, la elasticidad entre 0-10% y la ductilidad en más de un 150%. Por tanto, la adición de estos elementos es beneficiosa para las propiedades mecánicas. El análisis estadístico muestra que el efecto de la temperatura y presión son importantes mientras que el efecto del tiempo es poco significativo e incluso perjudicial en estas aleaciones. Palabras clavePulvimetalurgia; Aleaciones de titanio; Ti-Nb; Ti-Ta.Effect of process variables on the flexural behavior of alloys Ti -3% at. X (X = Nb, Ta) obtained by powder metallurgy AbstractNiobium and tantalum are added to titanium alloys to form new beta alloys with higher biocompatibility for biomedical applications. Both elements have a high melting point, that is the reason for their limited solid state diffusion. In this work samples of titanium with 3% at. niobium and tantalum have been manufactured by powder metallurgy. The effect of the compacting pressure, temperature and the sintering time on the strength, elasticity and ductility in bending has been studied. The results show that both elements behave similarly: flexural strength increases between 20-25%, elasticity between 0-10% and ductility over 150%. Therefore, the addition of these elements is beneficial to mechanical properties. ...

Laser cladding is an adequate technique to fabricate Metal Matrix Composite (MMC) layers because of its focused high energy which allows the partial melting of hard ceramic reinforces particles like carbides. Thus, the wettability and gradual transition between metal and particle can be improved. However, metastable or new intermetallic phases can be formed during laser processing due to severe thermal cycle imposed to the clad with unknown properties in some cases. In this work our experience on microstructural analysis of Ti-MMC coatings acquired during the last five years is summarized. Special attention is paid on carbide dilution and secondary carbides formation mechanisms when TiC, SiC, Cr3C2, WC and B4C are mixed with titanium alloys.

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Abstract. Network governance is described as a framework of policies and business rules, which is applied to manage an extended organization. Nowadays, one of its main concerns is risk management (RM) and the operational risk mitigation is crucial to avoid disruptions, delays and quality fades. Single sourcing can be interesting to reduce economic costs enabling the product design but at the same time can synergize the above-mentioned risks. Traditional RM approach for sourcing risks is based on selecting reliable partners, sharing knowledge and creating standard procedures that need to be complied. But the development of sensing networks based on early-warning systems (EWS) based on performance metrics to support decisions will be a promising alternative