On Laves phase in a 9Cr3W3CoB martensitic heat resistant steel when aged at high temperatures  

作　　者：Ye Liang Wei Yan Xianbo Shi Yanfen Li Quanqiang Shi Wei Wang Yiyin Shan Ke Yang 

机构地区：[1]Shi-changxu Innovation Center for Advanced Materials,Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110016,China [2]School of Materials Science and Engineering,University of Science and Technology of China,Shenyang 110016,China [3]CAS Key Laboratory of Nuclear Materials and Safety Assessment,Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110016,China

出　　处：《Journal of Materials Science & Technology》2021年第26期129-140,共12页材料科学技术（英文版）

基　　金：financially supported by the National Natural Science Foundation of China(No.51971226);the National Basic Research Program of China(No.2017YFB0305201)。

摘　　要：9Cr3W3 CoB steels are developed to serve at the temperature range of 620-650℃,and have been recognized as the most promising martensitic heat-resistant steels for supercritical power plants.Due to the high W and Co contents,the Fe_(2)W Laves phase in such 9Cr3W3 CoB steel possesses some specialties in thermodynamics.In the present research,it was found that even when aged at 800℃in the 9Cr3W3 CoB steel,instead of dissolving,Laves phase formed after 50 h and kept on increasing in size and number density until 1000 h,indicating that the Laves phase was marching for the thermodynamic equilibrium during aging.In this thermodynamic process,the W-rich M_(3)B_(2)borides in as-received steel and M23C6 carbides were revealed to dissolve,supporting the growth of Laves phase.SEM investigation indicates that Laves phase tended to form clusters,and finally grow as a unit bulk Laves phase with an irregular shape.Besides,Laves phase nucleated next to M23C6 carbides and enwrapped them inside at 800℃.In addition,the growth processes of Laves phase and M23C6 carbides were a competitive procedure,the coarsening of M23C6 carbides was prior to the growth of Laves phase at 750℃while the growth of Laves phase was prior to the coarsening of M23C6 carbides at 800℃.

关 键 词：9Cr3W3Co steel AGING Laves phase COBALT M23C6 carbides 

分 类 号：TG142.73[一般工业技术—材料科学与工程]