This paper describes direct cladding of magnesium (Mg) and aluminum (Al) alloys using a tandem horizontal twin roll caster that has three pairs of upper and lower rolls. Manufacturing conditions that are appropriate for fabricating Al/Mg and Al/Mg/Al cladded material were investigated. The surface condition of the cladded cast strip was examined. An electron probe micro analyzer was used to observe the interface between Al alloy and Mg alloy. The thickness of the mixed layer of Al and Mg alloy was 15μm, and how the materials were connected was clarified. Microscopic observation and backscattered electron analysis were used to investigate the cladding mechanisms of the Al and Mg alloy layers. Average hardness was determined using the Vickers hardness test at the Al layer and at the diffused layer between Mg and Al alloys. Cladding of Al/Mg alloy and A/Mg/Al alloy was possible using a tandem twin-roll caster. In addition, Al3Mg2 and Al12Mg17 phase precipitation at the interface of the Al and Mg alloys was confirmed during direct cladding from molten metals.
The electric resistance of oxide films formed on various Zr alloys in steam at 673 K and in BWRs were measured by an a-c impedance method to investigate the mobilities of the electric charges. The effects of oxide microstructure on transport of electric charges were investigated by TEM.
Impedance responses differed significantly between unirradiated pre- and post-transition films, although TEM observations gave no clear difference in crystal shapes and sizes of the oxide films. The results of a-c impedance measurements showed that the pre-transition oxide films had a fairly low electronic conductivity. This high resistance corresponded to the presence of a space charge layer near the outer surface of the oxide films which was in contact with the electrolyte. On the other hand, electronic conductivity of post-transition oxide films was about a thousand times higher than that of the pre-transition films.
The a-c impedance method was applied to ten kinds of Zr alloys irradiated in a BWR for four cycles. Only high Fe,Ni/Zry-2 and high Fe/Zry-2 alloys indicated responses similar to those of unirradiated pre-transition oxide films. This implied good corrosion performance for up to four irradiation cycles without oxidation rate transition. Furthermore, the alloys whose oxide had a lower electronic conductivity showed a smaller weight gain.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.