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研究了Ti45Al8Nb0.8B0.2C合金的组织及高温氧化行为。XRD、SEM、TEM及EDS分析表明,合金热等静压后的组织为γ和α2相组成的片层组织,片层团晶粒内部与层片团晶界处存在条状或点状白色相TiB2;高温淬火合金发生α→γm相变,在α+γ两相区时效合金组织由不同取向的细小层片和层片交界处的α2相组成。氧化增重实验及XRD、SEM分析表明,合金在900和1000℃氧化100h,氧化反应常数分别为0.00192和0.31637,幂指数分别为1.1381和2.0076。合金在900℃氧化100h后氧化层厚度大约为4μm,从外到内依次为:不连续的Al2O3层/Al2O3+TiO2混合层/富Nb层/基体。合金在1000℃氧化100h后氧化层厚度大约为5μm,从外到内依次为:TiO2/Al2O3+TiO2/氮化物层/基体。
The microstructure and high temperature oxidation behavior of Ti45Al8Nb0.8B0.2C alloy were studied. The results of XRD, SEM, TEM and EDS show that the microstructure of the alloy after hot isostatic pressing is a lamellar structure composed of γ and α2 phases. The lamellar or punctate white phase TiB2; α → γm phase transformation occurred in the high temperature quenched alloy, the α + γ phase in the α + γ two-phase region of the aging alloy microstructure by the different orientation of the small layer and the layer at the junction of the layer. Oxidation weight gain experiments and XRD and SEM analyzes showed that the oxidation constants of the alloys were 0.00192 and 0.31637 respectively at 900 and 1000 ℃ for 100h, and the power exponents were 1.1381 and 2.0076, respectively. The thickness of the oxide layer after oxidation at 900 ℃ for 100h is about 4μm. From outside to inside, the discontinuous Al2O3 layer / Al2O3 + TiO2 mixed layer / Nb-rich layer / matrix. The thickness of the oxide layer is about 5μm after oxidation at 1000 ℃ for 100h. The order of the outer layer is: TiO2 / Al2O3 + TiO2 / nitride layer / matrix.