| 摘要 |
A superhard polycrystalline construction, such as polycrystalline diamond, is disclosed which comprises a body of polycrystalline superhard material having a first region 41,42 and a second region 46 adjacent to and bonded to the first region by intergrowth of grains of superhard material. The first region comprises a plurality of alternating layers, each having a thickness in the range of around 5 to 300 microns. One or more layers in the second region have a thickness greater than the thicknesses of the individual layers in the first region. The alternating layers in the first region comprise first layers alternating with second layers, the first layers being in a state of residual compressive stress and the second layers being in a state of residual tensile stress. One or more of the layers in the first or second regions comprise a mass of superhard grains exhibiting inter-granular bonding and defining a plurality of interstitial regions therebetween, the superhard grains and a non-superhard phase at least partially filling a plurality of the interstitial regions. The median of the mean free path associated with the non-superhard phase divided by (Q3-Q1) for the non-superhard phase is greater than or equal to 0.50, where Q1 is the first quartile and Q3 is the third quartile; and the median of the mean free path associated with the superhard grains divided by (Q3-Q1) for the superhard grains is less than 0.60. A method of forming the construction is also disclosed. |
