The microstructure, room-temperature fracture toughness and high-temperature oxidation resistance of Nb-16Si-23Ti-4Cr-2Al-2Hf-xEr (x = 0, 0.1, 0.4, 0.6, at.%) alloys via directional solidification and heat treatment were investigated. Results showed that all the alloys consisted of Nb_ss, αNb₅Si₃ and γNb₅Si₃ phase, Er addition refined the microstructure, increased the volume fraction and continuity of Nb_ss matrix. Since the high-activity of Erbium, it is in-situ oxygenated to form a mixed oxide phase in the form of discreet particles, alloy melt got purification by internal oxidation mechanism. The higher density dislocations which may be induced by thermal expansion mismatch were piled up around the oxide particle compared with other regions in Nb_ss matrix. Er-doping contributed to eliminate segregation of Ti and then reduced its concentration-sensitive effect. Besides, more Nb_ss/silicide interface decohesion was triggered by addition of Er. So the 0.4 at.% Er addition significantly enhanced the fracture toughness of NbSi based alloys from 8.4 MPa·m^1/2 to 24.5 MPa·m^1/2 at room temperature. Er also accelerated the formation of complex oxide products and transition from linear oxidized regularity to parabolic, and obviously decreased the weight gain from 258.2 mg/cm² to 164.3 mg/cm² after oxidation at 1300 °C for 100 h.

Nb-16Si-23Ti-4Cr-2Al-2Hf-xEr（x = 0，0.1，0.4，0.6，at。％）合金通过定向凝固和热处理的微观结构，室温断裂韧性和高温抗氧化性被调查了。结果表明，所有的合金由铌的_SS，αNb ₅的Si ₃和γNb ₅的Si ₃相，二加成细化微观结构，增加Nb的体积分数和连续性_SS矩阵。由于of的高活性，它被原位氧化形成离散颗粒形式的混合氧化物相，合金熔体通过内部氧化机理得到纯化。与Nb _ss矩阵中的其他区域相比，氧化物颗粒周围堆积了可能由热膨胀失配引起的更高密度的位错。掺Er有助于消除Ti的偏析，进而降低其对浓度的影响。此外，添加addition引发了更多的Nb _ss /硅化物界面脱粘。因此，添加0.4 at。％Er可以将Nb Si基合金的断裂韧性从8.4 MPa·m ^1/2大大提高到24.5 MPa·m ^1/2在室温下。Er还加速了复合氧化物产物的形成，并从线性氧化规则转变为抛物线形，并且在1300°C氧化100 h后，其增重明显从258.2 mg / cm ²降至164.3 mg / cm ²。