Thermal Conductivity of Chromium Alloys

T Shelton and Swanger (National Bureau of Standards), Trans. Am. Soc. Steel 

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Pure metals have high thermal conductivities, and one would think that metal alloys should also have high conductivities. One would expect an alloy made of two metals of thennal conductivities and 2 to have a conductivity k between A , and ki. But this turns out not to be the case. TTie thermal conductivity of an alloy of two metals is usually much lower than that of either metal, a.s shown in Table 1-2. Even small amounts in a pure metal of foreign molecules that are good conductors themselves seriously disrupt the transfer of heat in that metal. For example, the thermal conductivity of steel containing just 1 percent of chrome is 62 W/m °C, while the thermal conductivities of irort and chromium are 83 and 95 W/m C, respectively. 

This alloy is manufactured under the trade name of E-Brite by Allegheny Ludlum Industries, Inc. It is a high-chromium alloy. Refer to Table 8.1 for the chemical composition. Compared to the 300 series of stainless steel, alloy S44627 has a high thermal conductivity and a low coefficient of thermal expansion. 

In 1928, this copper metal-silieide alloy system was patented by Michael Corson [1]. It was subsequently known as Corson bronze. In tMs alloy, the silicide could be nickel, chromium or cobalt based. In copper, a small addition of silicon and nickel or eobalt in a stoichiometric ratio of 1 2 results in the formation of an X2Si silicide that has a significant strengthening effect on the copper while keeping thermal and electrical conductivity nearer that of pure copper. Likewise, chromium will form a Cr2Si3 silicide. However, with a Brinell hardness of only 135 (75 HRB), the simple silicide system found limited use. 

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