Structural variation, vitrification, and crystallization processes in liquid nickel are simulated on continuous cooling and isothermal holding using a classical molecular-dynamics computer simulation procedure with an embedded-atom method potential at constant pressure. Structural changes are monitored with direct structure observation in the simulation cells, as well as by pair distribution and radial distribution functions created using the atomic coordinates. A cluster analysis is also performed. The crystallization kinetics is analyzed under isothermal conditions by monitoring density and energy variation as a function of time. As a result, a time-temperature-transformation diagram can be constructed over a wide temperature range.