Tin cry
Encyclopedia
A tin cry is the characteristic sound heard when a bar of tin
is bent. Variously described as a "screaming" or "crackling" sound, the effect is caused by the crystal twinning
in the metal. The sound is not particularly loud, despite terms like "crying" and "screaming".
The tin cry is often demonstrated as a simple science experiment. The bar of tin will "cry" repeatedly when bent until it breaks. The experiment can then be recycled by melting and recrystallizing the metal. The low melting point of tin (only 232 °C, or about 500 K) makes re-casting easy. Tin anneals
at reasonably-low temperature as well, normalizing tin's microstructure
of crystallites/grains.
Although the cry is most typical of tin, a similar effect occurs in other metals, such as niobium
, indium
, zinc
and gallium
.
Tin
Tin is a chemical element with the symbol Sn and atomic number 50. It is a main group metal in group 14 of the periodic table. Tin shows chemical similarity to both neighboring group 14 elements, germanium and lead and has two possible oxidation states, +2 and the slightly more stable +4...
is bent. Variously described as a "screaming" or "crackling" sound, the effect is caused by the crystal twinning
Crystal twinning
Crystal twinning occurs when two separate crystals share some of the same crystal lattice points in a symmetrical manner. The result is an intergrowth of two separate crystals in a variety of specific configurations. A twin boundary or composition surface separates the two crystals....
in the metal. The sound is not particularly loud, despite terms like "crying" and "screaming".
The tin cry is often demonstrated as a simple science experiment. The bar of tin will "cry" repeatedly when bent until it breaks. The experiment can then be recycled by melting and recrystallizing the metal. The low melting point of tin (only 232 °C, or about 500 K) makes re-casting easy. Tin anneals
Annealing (metallurgy)
Annealing, in metallurgy and materials science, is a heat treatment wherein a material is altered, causing changes in its properties such as strength and hardness. It is a process that produces conditions by heating to above the recrystallization temperature, maintaining a suitable temperature, and...
at reasonably-low temperature as well, normalizing tin's microstructure
Microstructure
Microstructure is defined as the structure of a prepared surface or thin foil of material as revealed by a microscope above 25× magnification...
of crystallites/grains.
Although the cry is most typical of tin, a similar effect occurs in other metals, such as niobium
Niobium
Niobium or columbium , is a chemical element with the symbol Nb and atomic number 41. It's a soft, grey, ductile transition metal, which is often found in the pyrochlore mineral, the main commercial source for niobium, and columbite...
, indium
Indium
Indium is a chemical element with the symbol In and atomic number 49. This rare, very soft, malleable and easily fusible post-transition metal is chemically similar to gallium and thallium, and shows the intermediate properties between these two...
, zinc
Zinc
Zinc , or spelter , is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...
and gallium
Gallium
Gallium is a chemical element that has the symbol Ga and atomic number 31. Elemental gallium does not occur in nature, but as the gallium salt in trace amounts in bauxite and zinc ores. A soft silvery metallic poor metal, elemental gallium is a brittle solid at low temperatures. As it liquefies...
.