Embrittlement liquid metals

Cracking mechanisms in which corrosion is implicated include stress corrosion cracking, corrosion fatigue, hydrogen-induced cracking and liquid metal embrittlement. Purely mechanical forms of cracking such as brittle failure are not considered here. 

The presence of liquid mercury poses a liquid metal embrittlement problem for many alloys. This occurs by the spillage of mercury in aircraft and the condensation of mercury vapor from mercury pumps in cryogenic applications. 

Non-metallic impurities in liquid alkali metals play a major role in the corrosion of materials either by affecting metal solubilities, f orming spalli-ble corrosion products on the metal surface, promoting liquid metal embrittlement or bulk embrittlement of the surface or by sensitising the structure for further attack by other impurities e.g. O2. As in other corrosive environments the direction and magnitude of these impurity reactions... 

Chemical reaction This involves the formation of distinct compounds by reaction between the solid metal and the fused metal or salt. If such compounds form an adherent, continuous layer at the interface they tend to inhibit continuation of the reaction. If, however, they are non-adherent or soluble in the molten phase, no protection will be offered. In some instances, the compounds form in the matrix of the alloy, for example as grain-boundary intermetallic compound, and result in harmful liquid metal embrittlement (LME) although no corrosion loss can be observed. 

Prerequisites for liquid-metal embrittlement are that a solid metal should be subjected to tensile plastic strain while wetted by a liquid metal in which it has low solubility. It has been suggested that such embrittlement may be a general phenomenon occurring under appropriate conditions and to varying degrees between all solid-metal/liquid-metal couples and that a... 

Liquid Metal Embrittlement the embrittlement of a metal or alloy as a consequence of contact with a liquid metal, resulting in the formation of cracks. 

Where very high temperatures are involved, the presence of copper deposits may cause liquid metal embrittlement. 

Liquid metal embrittlement copper traces are present. Results from copper deposits and high temperature conditions. 

My own criticism on the theories proposed for superplasticity can be summarized in one word, electrons , or more accurately the lack of electronic consideration. This is similar to the theoretical consideration brought forward in the study of LME (liquid metal embrittlement) described in the previous chapter - no electronic consideration. As shown in Table 2, all superplastic alloys of binary system are found either at eutectic or eutectoid compositions. This is illustrated in Fig. 14 in which a few binary phase diagram involving superplastic alloys are shown. However, the people who made efforts in the formulation of theories did not consider this well-known fact important enough to incorporate into their theory formulation [24], In fact, this observation is so consistent one should ask the question of the special attributes associated with eutectic or eutectoid composition. Or the fact that the intermetallic compounds with superelastic property are all of the peritectic type. It must be emphasized that to this date there is no report of finding superplasticity in congruently-melting compounds. 

Some cadmium-plated bolts and nuts were purchased and installed as a test in the plant. More bolts were purchased and eventually some of the cadmium-plated bolts were installed on the outlet piping flanges of a cracking furnace. The high temperature outlet flanges on the furnace started to weep a bit. An experienced, intelligent pipefitter attempted to snug up a few bolts and the nuts crumbled. (The cause of the failure was later determined to be due to corrosion phenomena called liquid metal embrittlement. )... 

Corrosion, temperature Liquid metal embrittlement, hot corrosion, dealloying... 

Zirconium alloys are also susceptible to liquid metal embrittlement in metals such as Li, Cs, Cd, Cs/Cd, Cs/Ca, Cs/Y, Cs/Zn, Ag, Hg and Ga and the cracking of the zirconium alloys are transgranular, with the exception in Ga and Cd where the intergranular mode has been observed.105... 

The proponents of this model reasoned that similar fracture processes occur in liquid-metal embrittlement, hydrogen embrittlement, and S.C.C., with chemisorption facilitating the nucleation of dislocations at the crack tip and promoting the shear processes that result in brittle, cleavage-like fracture. It was found that cleavage fracture occurs by alternate slip at the crack tip and formation of voids ahead of the crack tip [35-37]. 

Stress-sorption cracking is the basic mechanism applying to stress cracking of plastics by specific organic solvents [41, 42] and to liquid-metal embrittlement—the cracking of solid metals by specific liquid metals. It is also the mechanism proposed earlier by Fetch and Stables [43] to account for stress cracking of steel induced by interstitial hydrogen (see Section 8.4). 

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