Effect of tin addition on Nb-Si-based in situ composites. Part I: Structural modifications - Archive ouverte HAL Access content directly
Journal Articles Intermetallics Year : 2014

Effect of tin addition on Nb-Si-based in situ composites. Part I: Structural modifications

S. Knittel
  • Function : Author
Stéphane Mathieu
Michel Vilasi

Abstract

This paper reports the effect of adding 2 to 8 at.%Sn on the microstructure of Nb-25Ti-8Hf-2Cr-2Al-16Si. The samples were synthesised by casting and were heat treated for 5 days at 1200 degrees C. The as-cast and heat-treated microstructures were characterised using X-ray diffraction, scanning electron microscopy and microprobe analysis. The results revealed strong microstructural changes when Sn content exceeded 2 at.% Sn. The two-phase (Nb,Ti)(SS)/gamma-M5Si3 composite evolves towards a quaternary phase equilibrium: (Nb,Ti)(SS) saturated with Sn/alpha-M5Si3/(Nb1-xTix)(3)(Sn1-yTiy)/(y)'-M5Si3. The gamma'-M5Si3 differs from the gamma-M5Si3 through its Hf and Ti contents. The (Nb,Ti)ss fraction decreases strongly, benefitting the (Nb1-xTix)(3)(Sn1-yTiy) fraction. Therefore, adding greater than 2 at.% Sn addition may dramatically affect the mechanical properties of Nb/Nb5Si3 composites because the solid solution (Nb,Ti)(SS) has been shown to dominate the toughness of such materials.
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Dates and versions

hal-01291817 , version 1 (22-03-2016)

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S. Knittel, Stéphane Mathieu, Michel Vilasi. Effect of tin addition on Nb-Si-based in situ composites. Part I: Structural modifications. Intermetallics, 2014, 47, pp.36-42. ⟨10.1016/j.intermet.2013.12.008⟩. ⟨hal-01291817⟩
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