Effect of boron addition on the microstructure and mechanical properties of K4750 nickel-based superalloy
来源期刊：JOURNAL OF MATERIALS SCIENCE TECHNOLOG2021年第1期
论文作者：Xiaoxiao Li Meiqiong Ou Min Wang Long Zhang Yingche Ma Kui Liu
文章页码：177 - 185
摘 要：The effect of boron addition at 0,0.007 wt.% and 0.010 wt.% on the microstructure and mechanical properties of K4750 nickel-based superalloy was studied.The microstructure of the as-cast and heat-treated alloys was analyzed by SEM,EPMA,SIMS and TEM.Lamellar M5 B3-type borides were observed in boroncontaining as-cast alloys.After the full heat treatment,boron atoms released from the decomposition of M5 B3 borides were segregated at grain boundaries,which inhibited the growth and agglomeration of M23C6 carbides.Therefore,the M23C6 carbides along grain boundaries were granular in boron-containing alloys,while those were continuous in boron-free alloys.The mechanical prope rty analysis indicated that the addition of bo ron significantly improved the tensile ductility at room tempe rature and stress rupture properties at 750℃/430 MPa of K4750 alloy.The low tensile ductility at room temperature of 0 B alloy was attributed to continuous M23C6 carbides leaded to stress concentration,which provided a favorable location for crack nucleation and propagation.The improvement of the stress rupture properties of boron-containing alloys was the result of the combination of boron segregation increased the cohesion of grain boundaries and granular M23C6 carbides suppressed the link-up and extension of micro-cracks.
Xiaoxiao Li1,2，Meiqiong Ou1，Min Wang1，Long Zhang1，Yingche Ma1，Kui Liu1
1. Institute of Metal Research, Chinese Academy of Sciences2. School of Materials Science and Engineering, University of Science and Technology of China
摘 要：The effect of boron addition at 0,0.007 wt.% and 0.010 wt.% on the microstructure and mechanical properties of K4750 nickel-based superalloy was studied.The microstructure of the as-cast and heat-treated alloys was analyzed by SEM,EPMA,SIMS and TEM.Lamellar M5 B3-type borides were observed in boroncontaining as-cast alloys.After the full heat treatment,boron atoms released from the decomposition of M5 B3 borides were segregated at grain boundaries,which inhibited the growth and agglomeration of M23C6 carbides.Therefore,the M23C6 carbides along grain boundaries were granular in boron-containing alloys,while those were continuous in boron-free alloys.The mechanical prope rty analysis indicated that the addition of bo ron significantly improved the tensile ductility at room tempe rature and stress rupture properties at 750℃/430 MPa of K4750 alloy.The low tensile ductility at room temperature of 0 B alloy was attributed to continuous M23C6 carbides leaded to stress concentration,which provided a favorable location for crack nucleation and propagation.The improvement of the stress rupture properties of boron-containing alloys was the result of the combination of boron segregation increased the cohesion of grain boundaries and granular M23C6 carbides suppressed the link-up and extension of micro-cracks.
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