Analysis of High-temperature Strength Effect of Mo-based Alloy Based on Bayesian Optimization

Core structural materials such as cladding in advanced nuclear reactors face harsh service environments such as high-temperature, and their comprehensive performance is one of the bottlenecks restricting the development of advanced reactors. Mo and its alloys are key candidate, but pure Mo suffers from a lack of high-temperature strength. Mo-based alloys are superior to pure Mo in terms of mechanical properties. Research found that the addition of a certain amount of Re, W, Ti, Zr, C and other elements will enhance the high-temperature strength of Mo-based alloys. The effects produced by the ingredients are very complex and cannot be found in great detail by testing. Now materials genetic engineering, based on the prediction of data-driven material properties and optimization, shortening the cycle of materials research and development, and thus speed up the process of the entire field. Thus a CNN regression model based on Bayesian optimization was constructed based on the data obtained from literature research and preliminary experiment. The collected Mo-based alloy dataset contained 220 samples and 38 compositions as well as test temperature characteristics of tensile with the target variable being tensile strength. Found that the Re, C, O, N, Ti, Zr, Nb, La, W, Hf, Ta, Si, and Ni have a higher weight on the target value, and C, Ti, and Zr positively affect the tensile strength. Re, O, N, La, W, Hf, Ta, Si, and N have a negative tendency to correlate the characteristics with the tensile strength. Using the R2 value as an evaluation metric, the model is able to achieve 0.832 6. Combined with correlation analysis and modeling prediction analysis, it is concluded that Ti, Zr, Re and La2O3 are beneficial to the enhancement of high-temperature tensile strength of Mo-based alloy. N and Si are not conducive to the enhancement of tensile strength of Mo-based alloy at high-temperature. According to the correlation analysis conclusion, the effect of the coupling of these compositions C-Zr, Nb-Hf-Ta, Ni-Si, N-O and Zr-Ti on the tensile properties of the materials at high-temperatures will be considered subsequently, along with the simultaneous enhancement of toughness. Subsequently, by analyzing the influence of the combination of two elements or three elements on the change of tensile strength, it can get the composition design scheme that the tensile strength of Mo-based alloy reaches a certain range under specific temperature conditions.