Hot deformation behavior of Laves phase NbCr2/Nb two-phase alloy and optimization of deformation process parameters based on response surface method

Abstract:

Laves phase NbCr2/Nb two-phase alloy has attracted extensive research attention due to its potential as high temperature structural materials. Based on the isothermal constant strain rate compression experimental data of the alloy at temperatures ranging from 1273 to 1473 K and strain rates ranging from 0.001 to 0.1 s^-1, the flow stress behavior of the alloy was analyzed, the thermal deformation activation energy Q, power dissipation efficiency η and instability factor were calculated, response surface models with the deformation process parameters as input variables and Q, η and as response targets was established, and the appropriate window conditions of deformation process parameters were obtained by multi-objective optimization. The results show that Laves phase NbCr2/Nb two-phase alloy is a positive strain rate and negative temperature-sensitive material. The values of Q, η and values fluctuate within the range of 157.0-659.3 J/mol, 0.01-0.81 and -0.6229-0.6359, respectively, which indicates that the plastic deformation capacity of the alloy is sensitive to the change of process parameters. The established response surface models for Q, η and have high prediction accuracy with the determination coefficients R² reaching 0.992, 0.999 and 0.953, respectively, and the average absolute relative errors AARE are 1.29%, 0.63% and 11.5%, respectively. The interaction order of deformation process parameters on Q (from large to small) is as follows: deformation temperature/strain rate>strain rate/true strain>deformation temperature/true strain, while the interaction order of deformation process parameters on η and is basically the same, that is, deformation temperature/strain rate>deformation temperature/true strain>strain rate/true strain. Based on the multi-objective optimization of low Q, high η and , the appropriate deformation process window conditions are 1440-1473K and 0.001-0.05s^-1, and the optimal deformation process window condition is around 1473K and 0.001s-¹. Microstructural verification under the optimal deformation process conditions confirms the correctness of the deformation process window conditions obtained through multi-objective optimization.