“…In summary, from the above XPS investigations and literature data [11,18,20], one may conjecture that the good corrosion resistance observed for Co29Cr7W alloys results from the presence in the passive film of both chromium species (i.e., Cr2O3 and Cr(OH)3) in significant amounts and of tungsten oxide species in a much lower amount. Conversely, In summary, from the above XPS investigations and literature data [11,18,20], one may conjecture that the good corrosion resistance observed for Co29Cr7W alloys results from the presence in the passive film of both chromium species (i.e., Cr 2 O 3 and Cr(OH) 3 ) in significant amounts and of tungsten oxide species in a much lower amount. Conversely, for Co21Cr8Mo7W, the XPS results, in correlation with reported data [16,17,19], revealed that the good corrosion behavior of this alloy is mainly due to the synergetic effect of Cr, W and Mo, which are present in the film as Cr 2 O 3 , Cr(OH) 3, WO 3 and MoO 3 .…”