Influence of minor boron on the microstructures of a second generation Ni-based single crystal superalloy
Influence of minor boron on the microstructures of a second generation Ni-based single crystal superalloy
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DOI：
10.1016/j.pnsc.2018.06.001
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发表时间：
2018-08
期刊：
影响因子：
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通讯作者：
Y. Zhao;Liu Chenguang;Yuanyuan Guo;Yanfei Liu;J. Zhang;Yu-shi Luo;D. Tang
中科院分区：
文献类型：
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作者：
Y. Zhao;Liu Chenguang;Yuanyuan Guo;Yanfei Liu;J. Zhang;Yu-shi Luo;D. Tang
硼作为微合金元素加入单晶高温合金中，强化低角晶界。然而，关于硼对单晶高温合金微观组织影响的系统研究报道有限。研究了硼对含3 wt% Re的两种ni基单晶高温合金铸态和热处理组织的影响。结果表明，添加0.02 wt%硼可显著提高（γ + γ′）共晶和m3b2硼化物的体积分数，同时显著减少微孔的数量。（γ + γ′）共晶由于m3b2硼化物的形成导致初始熔化温度较低而不能完全溶解。同时发现m3b2硼化物中富集了必不可少的强化元素Cr、Mo、W和Re，这可能降低了强化效果，引起高温蠕变过程中的应力集中。
Boron is added into single crystal superalloys as a micro-alloying element to strengthen low angle grain boundaries. However, systematic investigations on the effect of boron on microstructures of single crystal superalloys are limitedly reported. The effect of boron on as-cast and heat-treated microstructures was investigated in two experimental Ni-based single crystal superalloys containing 3 wt% Re. The current results indicated that the volume fraction of (γ + γ′) eutectic and M3B2borides was evidently increased, while the number of micropores was evidently decreased with the addition of 0.02 wt% boron. The (γ + γ′) eutectic could not be dissolved completely due to the lower incipient melting temperature caused by the formation of M3B2borides. Meanwhile, the M3B2borides were found to be enriched with indispensable strengthening elements Cr, Mo, W and Re, and this may lower the strengthening effect and cause stress concentration during high temperature creep.