摘要
采用透射电镜(TEM)、扫描电镜(SEM)对不同服役时间下的含Hf涡轮叶片典型部位的组织进行了观察与定量表征,采用能谱分析仪(EDS)对服役过程中的碳化物的成分变化进行了分析,并对不同服役时间叶片进行显微硬度测试,研究了含Hf涡轮叶片在服役过程中组织及性能的演化规律,并根据LSW理论对不同部位的服役温度进行了定量反推。结果表明:在高温高应力下,服役400,650 h的叶片均发生了明显的组织退化,作为主要强化相的γ'粒子由规则立方体形貌逐渐粗化长大为L,H型等较为复杂的粒子形态,其等效直径由0.53μm增大至0.64μm,粗化过程由Ostwald熟化机制与粒子聚集机制的共同控制;其中,叶身中部粗化现象最为严重,经反推,其服役温度可达1180K;碳化物由富Ti-Ta的MC(1)型转变为富Hf的MC(2)型,并析出少量M23C6型碳化物,Hf元素在一定程度上抑制了M6C及TCP相的析出;在晶内第二相与γ基体界面及筏排处出现少量蠕变空洞,即蠕变空洞在位错堆积前沿萌生;随着服役时间的延长,合金的显微硬度逐渐降低,发生明显软化。
Microstructure of turbine blade containing Hf served for different time was observed and quantitatively characterized using transmission electron microscope （TEM） and scanning electron microscope （SEM）, and the chemical composition of carbide was analyzed by energy dispersion spectrometer（EDS）. The micro-hardness of the blade served for different time was tested. Microstrncture and property evolution of turbine blade containing Hf was investigated and the service temperature of typical parts of blade was calculated by LSW theory. The results showed that the microstrncture degenerated obviously under high temperature stress after serving for 400 and 650 h. γ＇ precipitates, the major strengthening phases, were coarsened and gradually turned into L or H-like particles from cubic morphology. The feret diameter increased from 0.53 to 0.64 μm through the mechanism of Ostwald ripening and particles agglomera- tion. The microstrncture of the middle part degenerated most seriously and the service temperature was estimated to be 1180 K. MC（1） carbides enriched with Ti-Ta decomposition during service and transformed into Hf-enriched MC（2）. A small amount of M23 C6 could also be seen in the served blade. The existence of Hf prevented the precipitation of M6C and TCP phase to some extent. A small amount of creep cavities were found on the boundary of intragranular second phases, initiating in the front of dislocation pile-ups. The microhardness of blade decreased with the increase of service time indicating the obvious softening effect.
出处
《稀有金属》
EI
CAS
CSCD
北大核心
2014年第3期354-362,共9页
Chinese Journal of Rare Metals
基金
中航工业产学研合作创新工程项目(201110026-01)资助
关键词
服役损伤
γ'粗化
碳化物退化
蠕变空洞
service induced degradation
γ＇ phase coarsening
carbide decomposition
creep cavity
