The mixed crystal Ar1-x(N-2)(x) was studied by molecular dynamics simulations in the NPT ensemble for three selected concentrations. The alpha <---->beta transition was not observed, instead the low temperature alpha phase shows a transition to a plastic fcc phase. The mixed crystals with fee arrangement tend to form orientationally ordered crystals. An orientational glass was obtained and characterized for x similar or equal to 0.7 and with an hcp structure in agreement with the experimental observations,