Molibdenum Alloys

The most important alloy of molybdenum is ferro- molybdenum, which is used as an addition to steel. The effect of molybdenum on steel is similar to that of tungsten, but is more marked; the tensile strength is increased and the elastic limit raised. For highspeed tool-steels molybdenum is often used in conjunction with tungsten. It has been found that the addition of molybdenum in small quantities (up to 15 per cent.) to steel increases the liability to corrosion, especially in acid and salt solutions. An important use of steels containing 3 to 4 per cent, of molybdenum and 1.0 to 1.5 per cent, of carbon is for the manufacture of permanent magnets.

With copper, molybdenum forms a greyish-red hard alloy, of density 7.934.

Silver and gold do not alloy with molybdenum; platinum can take at least 16 per cent, of the metal into solid solution near the melting-point, but on cooling the molybdenum separates out.

With mercury, alloys corresponding to the formulae MoHg₉, MoHg₂, and Mo₂Hg₃ have been described.

With aluminium, a number of alloys are formed, the compositions of which agree with the formulae Al₇Mo, Al₄Mo, Al₃Mo, Al₂Mo, AlMo, and AlMo₄; the existence of the alloy AlMo₂O is also suspected.

Alloys with chromium and with bismuth have been obtained in the electric furnace.

Alloys of molybdenum with other elements are dealt with in other volumes of this series.