No phase diagram is available for the Cu-K system. There are two recent critical evaluations of the system made by [1996Bor] and [1994Pel]. Both of them refer to the work by [1961Kie], according to which no intermediate phase is formed in the system. [1996Bor] also quotes the work by [1982Ale] where copper solubility in liquid potassium is reported to be extremely small.
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