Homologous temperature

The homologous temperature describes the ratio of the temperature of a substance to its melting temperature : ${\displaystyle T_{\mathrm {H} }}$ ${\displaystyle T}$ ${\displaystyle T_{\text{S}}}$

${\displaystyle T_{\text{H}}={\frac {T}{T_{\text{S}}}}}$

The thermodynamic temperature in Kelvin is used:

Above a certain homologous temperature of at least 0.3 to 0.4 , metals creep under stress, i. H. their elongation increases over time. This is e.g. This is important, for example, in electronic applications in which structures made of different metals (e.g. copper coating, lead solder, aluminum or gold wire) have to withstand large temperature differences.

Examples

The homologous temperature of lead at room temperature ( ) is 0.50 because the melting temperature is. ${\displaystyle 25\,\mathrm {^{\circ }{\text{C}}} =298{,}2\,\mathrm {K} }$ ${\displaystyle T_{\text{S}}=327{,}4\,\mathrm {\;^{\circ }{\text{C}}} =600{,}6\,\mathrm {K} }$

In contrast, the homologous temperature of copper at room temperature is only 0.22 ( ). ${\displaystyle T_{\text{S}}=1084{,}6\,\mathrm {^{\circ }{\text{C}}} =1357{,}8\,\mathrm {K} }$

Individual evidence

1. ↑ ^{a b} J. Rösler, H. Harders, M. Bäker: Mechanical behavior of materials . 2nd edition, Springer, 2006, ISBN 3-8351-0008-4 , p. 383.