Reactive sintering of crushed metals and carbon is advantageous for preparing toughened complete solid-solution cermets (CSCs). Here, dual-grained (Ti-0.6, W-0.4)C-18Ni cermets were prepared using a two-step carbonization method. High-energy milling of Ni-Ti-W-C (Ni(Ti-0.6, W-0.4)(4)C) mixture afforded NiTiW solid solution, which was then transformed into Ni6W6C by heating at 1250 degrees C. Twinned (Ti, W)C platelets were formed by the carbonization of Ni2W4C during liquid sintering. W atoms that accumulated in the (111) planes of TiC promoted the {111} twin formation, leading to sandwich-type (Ti, W)C platelets. Dense (Ti-0.6, W-0.4)C-18Ni cermets were obtained by hot isostatic press sintering in Ar with satisfactory Hv of 12.8 +/- 0.2 GPa, high strength of 1960 +/- 84 MPa and toughness of 15.80 +/- 0.6 MPam(1/2). A higher sintering temperature or graphite content accelerated the carbonization, resulting in coarser platelets with decreased aspect ratio. This study provides a new approach to modify the microstructure of CSCs and a method for preparing dual-grained cermets.