VALENZA , F.

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A crystallochemical study was undertaken to investigate the structural stability and the compositional extent of the ternary borides M2(Ni21-xMx)B6 (M = Ti, Zr, Hf). This phase often occurs during the production of MB2 joints by means of NieB brazing alloys. Samples with the nominal compositions M2Ni21B6 and M3Ni20B6 were synthesized by arc...

Aiming to evaluate the effect of refractory metal additions to a quinary AlCoCrFeNi High-Entropy Alloy (HEA), three novel equimolar AlCoCrFeNi-X (X = Mo, Ta, W) HEAs were designed, arc-melted, annealed, and characterized by SEM-EDS, XRD and microhardness measurements. CALPHAD thermodynamic calculations were exploited to design compositions and...

The YAG/filler/Ti6Al4V system has been studied for the first time with the aim of producing brazed optical windows. Different fillers (AgCuTi, AgCu, Ag) and temperatures have been taken into account and the interfacial zones of the samples have been evaluated in terms of morphology and compositions. A thin and continuous metal-ceramic layer...

Within the context of the design of high-temperature brazing process for C and SiC-based composites, a basic study is presented here about the wetting and interfacial reactivity of Co–Ta alloys in contact with graphite or SiC. Wetting results are presented for the first time showing that Co–Ta alloys wet C or SiC fairly or excellently depending...

Several industrial processes involving SiC coupling to Al–Ti alloys (e.g. metallization of SiC components, brazing of SiC parts) require an in-depth knowledge of Al–Ti/SiC interactions occurring at high temperatures. To this end, the surface reactivity between SiC and Al–Ti alloys (Al3Ti and (Al + Al3Ti) systems) was analyzed by specific...

Corrosion is an important issue for alloys in natural seawater, where microorganisms can accelerate or mitigate corrosion. Al-Mg alloys are used for marine activities and various associated technologies. Here, the behaviour of AA5083 alloy was investigated in natural seawater with marine exposure lasting up to 50 days and detailing the first 8...