Superhard constructions and methods of making same

A method of forming a super hard polycrystalline construction comprising:

• forming a pre-sinter assembly comprising:
• a first mass of grains or particles of a super hard material;
• a source of catalysing material for the first mass of grains or particles of super hard material;
• a further mass of grains or particles comprising diamond grains or particles mixed with a non-super hard material;
• and
• a mass of grains or particles of a material to form a substrate;
• treating the pre-sinter assembly at an ultra-high pressure of around 5 GPa or greater and a temperature to bond together the grains of super hard material in the first mass to form a first region comprising a body of polycrystalline super hard material bonded to a further region formed of substantially non-interbonded diamond grains or particles in the further mass;
• the further region being bonded to the substrate along an interface, the interface comprising a portion having an uneven topology and a substantially planar portion, the further region forming an intermediate region between the first region and the substrate and comprising:
• a composite material including:
• a first phase comprising a plurality of non-intergrown diamond grains, and
• a matrix material.