目的 进一步改善新型低密度难熔高熵合金NbMoCrTiAl-1Si的高温氧化能力。方法 采用非自耗真空电弧熔炼技术配合水冷铜模制备了NbMoCrTiAl-1Si-xB(x=0、1)合金，于1173 K下，在TGA/DSC1型热重及同步热分析仪上进行了48 h高温氧化试验，通过XRD、SEM及EDS分析了该合金的组织结构和高温氧化机制。结果 铸态NbMoCrTiAl-1Si-xB(x=0、1)合金具有典型的枝晶状组织，1% B元素的添加不会改变合金枝晶的组织结构，但会使枝晶间组织形态由黑色纳米颗粒状转变为亮白色短棒状。NbMoCrTiAl-1Si合金的氧化过程由初期线性快速氧化阶段和后期抛物线慢速氧化阶段组成，氧化总增重为1.064 mg/cm2，而NbMoCrTiAl-1Si-1B合金氧化过程则可分为具有两个不同氧化速率常数的抛物线氧化阶段，氧化总增重约为NbMoCrTiAl-1Si合金氧化总增重的1/2。经48 h高温氧化后，NbMoCrTiAl-1Si合金表面氧化膜凹凸不平，枝晶间发生了明显的内氧化现象，形成了枝晶内以片状和针状刚玉结构的Al2O3为主，枝晶间以团簇状金红石结构的TiO2为主的氧化膜，NbMoCrTiAl-1Si-1B合金表面氧化膜相对平坦，整个试样表面覆盖了一层由Al2O3、TiO2和Ti0.4Al0.3Nb0.3O2等组成的连续、致密的氧化膜。结论 1% B元素的添加会促进NbMoCrTiAl- 1Si-1B合金表面Al2O3和TiO2等致密氧化物的形成，抑制合金内氧化进程，显著提高合金抗高温氧化能力。

The work aims to further enhance the high temperature oxidation resistance of new low density refractory high-entropy alloy (RHEA) NbMoCrTiAl-1Si. NbMoCrTiAl-1Si-xB (x=0, 1) was prepared by non-consumable vacuum arc melting technology and the high temperature oxidation tests were conducted at 1173 K for 48 h in METTLER TOLEDO TGA/DSC1 thermogravimetric simultaneous thermal analyzer. The microstructure and high temperature oxidation resistance of the alloy were investigated by XRD, SEM and EDS. The results showed that the microstructure of as-cast NbMoCrTiAl-1Si-xB (x=0, 1) alloy had the characteristic of dendritic morphology. The addition of 1% B did not change the dendritic microstructure, but transformed the interdendritic microstructure from the black nanoparticles in NbMoCrTiAl-1Si alloy into the bright short- rod shape in NbMoCrTiAl-1Si-1B alloy. The oxidation process of NbMoCrTiAl-1Si alloy was divided into the initial linear rapid oxidation stage and the following parabolic slow oxidation stage with the total oxidation weight gain of 1.064 mg/cm2, whereas the oxidation process of NbMoCrTiAl-1Si-1B alloy consisted of parabolic slow oxidation stages with different oxidation rate constants and its total oxidation weight gain was about one-half of that of NbMoCrTiAl-1Si alloy. After oxidized at high temperature for 48 h, the obvious internal corrosion was observed in the interdendritic zone of NbMoCrTiAl-1Si alloy and the rough oxide film was formed on the surface mainly with the flaky and needle-like Al2O3 in the dendritic zone and TiO2 clusters in the interdendritic zone, while the continuously dense flat oxide film was formed on the surface of NbMoCrTiAl- 1Si-1B alloy mainly including Al2O3, TiO2 and Ti0.4Al0.3Nb0.3O2. Therefore, the addition of B can accelerate the formation of the dense oxides of Al2O3 and TiO2 on the surface of NbMoCrTiAl-1Si-1B alloy, thus inhibiting the internal oxidation, and greatly enhancing the oxidation resistance of NbMoCrTiAl-1Si-1B alloy.