增材制造单晶镍基高温合金微观组织、热稳定性及耐磨性能

Microstructure,thermal stability and wear resistance of additively manufactured single crystal Ni-based superalloys

利用定向能量沉积的增材制造方法制备了单晶镍基高温合金SRR99,通过微观组织表征、硬度测量与纳米划痕实验,系统地研究激光增材制造单晶镍基高温合金在服役温度下的组织稳定性。结果表明:经过服役温度(650℃)退火100 h后,增材制造样品γ'强化相的形貌及尺寸(70 nm)依旧保持。相比于传统铸造样品,服役温度退火前后增材制造样品的硬度(6.6 GPa)均提高了20%以上。此外,退火前后增材制造样品的摩擦因数均具有数值低(0.19)、离散性小的特点。本研究证明定向能量沉积增材制造的单晶镍基高温合金样品拥有优异的组织热稳定性和耐磨性能,为激光增材制造技术应用于单晶镍基高温合金涡轮叶片的榫头修复与提性延寿提供了实验支撑。

The single crystal Ni-based superalloy SRR99 was fabricated by laser-directed energy deposition(LDED).Through microstructural characterization,hardness measurements and nanoscratch tests,the microstructural stability of LDED single crystal Ni-based superalloy at the service temperature was systematically investigated.The results show that the morphology and size(70 nm)of theγʹprecipitates in LDED samples remain stable after annealing at the service temperature(650℃)for 100 h.The hardness values of LDED samples keep almost unchanged(6.6 GPa)before and after annealing,and are more than 20%higher than that of the traditional cast samples.Furthermore,the coefficients of friction of the LDED samples before and after annealing are lower(0.19)and less scattering than those of their cast counterparts.This study demonstrates that Ni-based superalloy single crystals fabricated by LDED exhibit excellent thermal stability and friction properties,paving the way to the application of LDED technology in the repair and life extension of single-crystalline turbine blade dovetails.