Semiviscosity flow equation with variable parameters under superplastic tension conditions

The accurate multinomial expression of the relation of of the three typical superplastic alloys is given. Then by means of the analytic expression of the constitutive parameters and, the semiviscosity flow equation in whichm andk are both variable can be obtained. And the equation includes the three parametersm _m ,m _k and η, which are related to the curve of. Finally, it is pointed out that the bigger the values ofm, η andm _m /m _k , the better the superplasticity of alloys. Furthermore, the Backofen's equation is only one of the special cases of semiviscosity flow equations with variable parameters. Project supproted in part by the National Natural Science Foudnation of China.