Strength Versus Temperature Anomalies in Metals (PDF)

Perhaps the best-known aspect of the behavior of metals, and indeed of most materials, is that they weaken with temperature. This weakening is however a problem in some applications. Only tungsten for instance, with its naturally high melting-point, was suitable for the manufacture of the filaments of incandescent light-bulbs. Even then, it was necessary to add oxide particles having a yethigher melting-point in order to prevent the weakening effect of grain-growth. These are alloys however which can be said to be weakened by heat, but nevertheless 'hang on' to enough strength to perform their task. The real boon would be an alloy which actually, as it were, 'rose to the occasion'. Such a class of alloy exists, and is the subject of this book. It brings together everything which is known about the yield strength anomaly; both theoretically and experimentally.Keywords: Mechanical Properties, Materials Processing, Alloy, Materials Survey, Yield stressMost metals, indeed most materials, weaken as they get hotter, says Fisher, but he identifies and describes a class of alloys that does not. They are said to exhibit a yield-point anomaly, or a positive temperature dependence of the tensile strength, he says, and do weakened eventually with increasing temperature, but reach their peak strength at temperatures useful in gas turbines and other applications. He explains that the phenomenon arises from a blocking of the dislocation motions that mediate deformation processes, rather than some anomaly in the elastic modulus or some other intrinsic property.- Engineering- Materials science- Metals