Environmental Engineering Reference
In-Depth Information
Cu by molten lithium and the nonoccurrence of embrittlement of Al by molten
lithium support the postulate, as in the latter system several intermetallic com-
pounds form and none forms in the former two systems. Figure 7.3 shows the
phase relationships most commonly associated with embrittlement couples.
Embrittlement may not be observed in a possible embrittlement couple be-
cause the solid metal is quite ductile at the liquid metal temperature such that a
brittle crack cannot be initiated or propagated, or it is excessively soluble in the
liquid metal which leads to the blunting of the crack. Cadmium (m.p. 329
°
C)-
liquid indium (m.p. 165
C) is an example. In such cases, the embrittling liquid
metal may be dissolved in an ''inert carrier'' liquid metal of lower melting point.
Mercury does not embrittle cadmium; it dissolves indium up to 70 at. % at 25
°
C
and has been utilized as inert carrier for indium to effect LME in solid cadmium.
The variation in ductility of cadmium with varying indium content in mercury
carrier is shown in Fig. 7.4.
°
Figure 7.3
Phase relationships most commonly associated with embrittlement couples.
