The internal friction of dilute alloys of lead

Abstract

The internal friction and Young's modulus were measured for a series of single crystals of lead containing approximately. 01 to 1 atomic per cent of either Bi, Sn, or Cd. It was discovered that the internal friction was independent of strain amplitude up to a critical strain amplitude, at which point the internal friction increased and the modulus decreased with further increase in strain amplitude. At room temperature the resolved shear stress for this critical strain amplitude is approximately equal to .15 μϵ c where μ is the shear modulus, ϵ is the fractional difference in size between the solute and solvent atoms, and c is the fraction of the total number of atoms which are solute atoms. The data also agree well with results on the change in the critical shear stress with alloying content in copper crystals reported by Linde, Lindell, and Stade.