The densification behavior during reactive sintering of compacted Ti/Al composite powders prepared by
high energy ball milling
was experimentally investigated,and the thermodynamics and kinetics aspects were theoretically analyzed The results show that
high energy ball milling promotes the sintering densification process more effectively than other means,such as increasing the applied pressure,enhancing the sintering temperature,or prolonging the sintering time The longer the milling time is,the higher the relative density of the as sintered specimen The relative density of the TiAl alloy obtained by two step pressureless reactive sintering,i e ,630℃×2h pre sintering and 1250℃×8h final sintering,of the compacted Ti/Al composite powders milled for 3h was found to be as high as 99 87% The above effect of ball milling on the
sintering densification behavior of the Ti/Al composite powders can be attributed both to the refinement of the Ti,Al reactant phases and their crystallite grains,and to the enhanced stored energy in the powders due to lattice distortion and defects,which are responsible for the increase of the sintering driving force and kinetics factor,the shortening of the elemental diffusion distance,and the elimination of the kirkendall porosity