The reaction ball milling can produce the solid state amorphization of covalent ceramic, SiC, including the mechanical alloying (MA) of the elemental crystalline powder mixture of Si and C and the mechanical grinding (MG) of the commercial beta-SiC particle and MG of the nanocrystalline beta-SiC powder as synthesized via 'high-energy' MA. An increase in amorphous volume (X) by decreasing crystallite size (d) during MG is expressed by a relation of X=1-{d/(d+Delta)}(3) with the intercrystal thickness (Delta) of 1 nm. The rotating-arm reaction ball milling is used to synthesize natrocrystalline (nc) hydroxyapatite by MA of the powder mixture at 303 K, according to a reaction of 6CaHPO(4)(.)H(2)O+4Ca(OH)(2)-> nc-Ca-10(PO4)(6)(OH)(2)+8H(2)O with JMA exponent of 1. By employing the pulse electric discharge consolidation, the amorphous SiC powder compact shows a rapid densification during Newtonian viscous flow as expressed by an Arrhenius relation with the activation energy of 495 kJ(.)mol(-1),and then obtain the full densification at 2033 K under 100 MPa. The nanocrystalline hydroxyapatite powder with the crystallite size of 8 mu can be consolidated at full-density at 1023 K under 150 MPa, following a rapid shrinkage during superplastic flow from 900 K. The fracture toughness (K-IC), as deduced from the indentation microfracture method, is the high level of 13 MPa(.)m(0.5) for nanocrystalline SiC with 12 nm.