Abstract: All intermetallic phases have a tendency to atomic long-range ordering, according to the ordering energy, they may be permanently ordered (up to the melting-point) or reversibly ordered (up to a critical temperature). The paper considers ways of disordering intermetallic phases, in relation to the ordering energy and diffusivities, and some properties of partially ordered intermetallic phases (including mechanical properties) The kinetics of re-ordering of disordered starting material will be examined,including sluggishly ordering phases (which can be aided by concurrent irradiation). The circumstances under which a partially disordered intermetallic phase may transform into an amorphous form will be outlined.

Key words: Long-range order, ordering, disorder trapping partial order