Effect of temperature on the reactivity between a CoCrMoSi alloy and 55 wt% AlZn baths

The reactivity of metallic alloys with Al has important impacts in industrial components and in Co-based components has been associated with the Al–Co reactions. The reactivity between Al and a CoCrMoSi alloy was assessed by immersion tests in a 55 wt% AlZn bath and DSC tests of multilayered pure Al/CoCrMoSi specimens. Phases were identified by XRD analysis. Results showed that the synthesis of Al–Co compounds occurs at a temperature as low as 380 °C. Despite the higher corrosion resistance of the Laves phase the performance of CoCrMoSi component is compromised by the reactivity between Al and elements from the Co solid solution regions.

The reactivity between Co and Al accounts for the degradation of Co-based components immersed in 55 wt% AlZn bath. The synthesis of Co–Al compounds ignites at temperatures as low as 380 °CFigure optionsDownload as PowerPoint slideHighlights
► The reactivity between a CoCrMoSi alloy and the 55 wt% AlZn bath is ruled by Al–Co reactions.
► The exothermal synthesis of Co–Al compounds is ignited at temperatures as low as 380 °C.
► The performance of the CoCrMoSi alloy in Al rich baths is compromised by the reactivity of Co-based solid solution regions.