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Stresses generated by inhomogeneous distributions of inclusions in diamonds

1997; Elsevier BV; Volume: 6; Issue: 1 Linguagem: Inglês

10.1016/s0925-9635(96)00699-1

1879-0062

T. R. Anthony, Yue Meng,

Metal and Thin Film Mechanics

Inhomogeneous distributions of inclusions in diamond can generate long-range strains and therefore long-range stresses in a diamond crystal with maximum magnitudes approaching the crushing strength of the diamond. Depending on the compressive or tensile nature of these stresses at the diamond surface, the diamond can be either strengthened or weakened, respectively. The stresses generated by the inclusions are proportional to the average size of the inclusions as well as to their concentration. The distribution of inclusions within a diamond strongly influences the mechanical strength of the diamond. A diamond crystal is weakened by the presence of inclusions whose concentration decreases with increasing radius or by inclusions that are clustered about the center of the crystal. These are the usual cases in practice. In the case of multiple inclusions concentrated in a cluster at the center of the crystal, the weakening is very small if the overall diamond diameter is at least six times greater than the diameter of the central inclusion cluster. However, if the diameter of the central inclusion cluster is greater than 20% of the diamond diameter, the inclusion cluster may significantly weaken the diamond crystal. Finally, a single inclusion acting as a heterogeneous nucleus in the center of the crystal can significantly reduce the strength of a diamond if the inclusion occupies more than 1% of the total volume of the diamond.