On a discrepancy in modulus of elasticity as determined from separate resonance frequencies of a bar sintered from copper-coated iron powder

Iron powder particles were coated with a copper, compacted into a bar shape, sintered and machined. Bars were caused to resonate longitudinally, transversely edgewise and flatwise. Three separate determinations of elastic modulus were made from the resonance frequencies of these modes. Three different values of elastic modulus were obtained for each of the bars. The nature of the differences indicates that the bars possess an inherent “layered” structure with stiffness graded transversely to the compaction direction. This supports a recently considered hypothesis about the behaviour of powders.