徐鹏飞,张建飞,陈林,金自力,任慧平.生长速率对定向凝固NiAl-43V过共晶合金组织演变和室温断裂韧性的影响[J].稀有金属材料与工程,2020,49(4):1415~1421.[Xu Pengfei,Zhang jianfei,Chen lin,Jin zili,Ren huiping.Effect of growth rates on microstructure evolution and room temperature fracture toughness of directionally solidi?ed NiAl-43V hypereutectic alloy[J].Rare Metal Materials and Engineering,2020,49(4):1415~1421.]
生长速率对定向凝固NiAl-43V过共晶合金组织演变和室温断裂韧性的影响
投稿时间:2018-12-24  修订日期:2019-02-27
中文关键词:  NiAl-V过共晶  凝固组织  室温断裂韧性  韧化机制
基金项目:国家自然科学基金项目(No.51564041);内蒙古自然科学基金项目(No.2018MS05028);
中文摘要:
      本文采用高温度梯度液态金属冷却技术(LMC)制备了Ni-28.5Al-43V(at%)过共晶合金,利用光学显微镜(OM)、扫描电镜(SEM)和三点弯曲(3PB)测试对合金的组织演变和断裂韧性进行了研究。在温度梯度GL=310K/cm,生长速率V=6~150μm/s的实验条件下, NiAl-43V的凝固组织均为初生V枝晶+共晶组织(NiAl片层+V片层)。断裂韧性测试表明NiAl-43V过共晶合金最大室温断裂韧性相比NiAl合金提高了四倍。随着生长速率的增大室温断裂韧性从6μm/s的22.679 MPa.m1/2逐渐下降到150μm/s的18.422 MPa.m1/2。这是因为生长速率增大产生的细晶强化效应弱于初生V枝晶和胞间区域的增加对断裂韧性产生的不良影响。合金的断口形貌分析表明合金断裂为准解理断裂,在裂纹扩展中裂纹钝化、裂纹再形核、裂纹偏转、界面剥离、裂纹桥接和微裂纹键合韧化机制对提高NiAl-43V合金的室温断裂韧性做出了贡献。初生V枝晶的析出一定程度降低了合金的断裂韧性。
Effect of growth rates on microstructure evolution and room temperature fracture toughness of directionally solidi?ed NiAl-43V hypereutectic alloy
英文关键词:NiAl-V hypereutectic  Solidification microstructure  Room temperature fracture toughness  Toughening mechanism
英文摘要:
      In this paper, a Ni-28.5Al-43V (at%) hypereutectic alloy was prepared by liquid metal cooling technology (LMC), The microstructure evolution and mechanical properties of the alloy were investigated by optical microscopy (OM), scanning electron microscopy (SEM) and three-point bending (3PB) test. Under the experimental conditions(Temperature gradient GL=310K/cm, Growth rate V=6~150μm/s), the results show that the steady-state growth microstructure of NiAl-43V is composed of primary V dendrites and eutectic structure (NiAl lamellar +V lamellar). 3PB test shows that the maximum room temperature fracture toughness(RTFT) of NiAl-43V hypereutectic alloy is four times higher than that of NiAl alloy.The RTFT decreases from 22.679 MPa.m 1/2 at 6 μm/s to 18.422 MPa.m 1/2 at 150 μm/s as the growth rate increases.The reason is that the fine-grained strengthening effect caused by the increase of growth rate is weaker than the adverse effect of increased primary V dendrites and inter-cell regions on fracture toughness. Fracture morphology analysis of alloys indicates that alloy fracture is quasi-cleavage fracture.Crack blunting, crack renucleation, crack deflection, interfacial debonding, crack bridging and linkage of microcrack toughening mechanism contribute to the improvement of room temperature fracture toughness of NiAl-43V alloy in crack propagation. The precipitation of primary V dendrites reduces the fracture toughness of the alloy.
作者单位E-mail
徐鹏飞 内蒙古科技大学材料与冶金学院 1298823716@qq.com 
张建飞 内蒙古科技大学材料与冶金学院 zhangjianfei_vip@163.com 
陈林 内蒙古科技大学材料与冶金学院  
金自力 内蒙古科技大学材料与冶金学院  
任慧平 内蒙古新金属材料重点实验室  
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