ABSTRACT
Effect of Alloying Some solid metals are embrittled in their pure state, e.g., zinc by mercury and cadmium or aluminum by liquid gallium. On the other hand, pure iron is not embrittled by mercury and pure copper is relatively immune in liquid mercury (coarse-grained copper is embrittled). However, iron becomes susceptible to embrittlement in mercury if alloyed with more than 2% Si, 4% At, or 8% Ni (Fig. 7.8). The susceptibility of copper to embrittlement in mercury is increased many fold when alloyed with Zn, AI, Ge, or Si. The same has been observed for zinc alloyed with a small amount of copper or gold when embrittled in mercury. The increase in the yield strength of the material on alloying is considered responsible for the increased susceptibility. It is generally observed that the high-strength alloys are more severely embrittled than low-strength alloys based on the same metal. This has been shown true for a series of commercial aluminum alloys when wetted with Hg + 3% Zn amalgam and for AISI 4340 steel quenched and tempered to different hardness when wetted with molten lithium [1].
