Microstructure and hot ductility behavior of Ni-based superalloy U720Li with boron addition

• 作者: Guang-Di Zhao Fang Liu Xi-Min Zang Wen-Ru Sun
• 来源期刊: 稀有金属（英文版）
• 年，卷（期）: 2021,（5）
• 所属期刊栏目: ORIGINAL ARTICLES
• 页码范围: 1145-1154
• 页数: 10页
• 语种: 英文

摘要

High-alloyed superalloy U720Li is difficult to be processed through the conventional cast and wrought route.Boron is an important strengthening element for superal-loys,but the role of boron in the hot ductility of U720Li alloy is not clear.This study is focused on the effect of boron addition,in the range of＜0.0005 wt％-0.0240 wt％,on the microstructure and hot ductility behavior of superalloy U720Li.It is found that boron addition significantly increases the content of eutectic(γ+γ')and greatly affects the degree of continuity of the grain boundary eutectic(γ+γ')precipitation.Boron addition dramatically worsens the 1100℃tensile ductility of conventional cast U720Li alloy and causes a change in tensile fracture mode from transgranular to intergranular.The eutectic(γ+γ')represents the most effective site for crack initiation.Boron deteriorates the hot ductility mainly by promoting the continuous precipitation of eutectic(γ+γ')along the grain boundary.