高温高应变率耦合对DD407镍基单晶合金的性能影响

为了理解一种新型DD407镍基单晶高温合金在高温高应变率下的力学行为,利用CSS4410型电子万能材料试验机和具有高温高应变率耦合试验功能的Hopkinson压杆系统测试该合金在温度293~1 273K,应变率分别为0.001、1 000及4 000/s条件下的塑性流动特性,并对变形前后的试样进行金相和SEM微观分析。结果表明:DD407合金在高应变率下的使用温度不能超过1 073K;其在压缩情况下的破坏均为剪切破坏;在温度接近或超过某一临界值,该材料的屈服强度和塑性流动应力对温度和应变率才会有很强的敏感性,与常规金属不同,该材料应变时效现象不明显。

Effect of High Temperature and High Strain Rate Coupling on the Property of Single-Crystal Nickel-Base Superalloy DD407

To understand the mechanical behavior of a new single-crystal nickel-base superalloy DD407 at high temperatures and strain rates,the CSS4410 quasistatic test machine and Hopkinson pressure bar systems are used to test the plastic deformation characteristics at strain rates of 0.001、1 000、4 000/s and initial temperature range from 293 Kto 1 273 K.In addition,based on SEM,the microstructure analysis of the un-deformed and post-deformed samples is performed.Results show that：firstly the working temperature of this superalloy cannot exceed 1 073 Kunder high strain rate;secondly the failure mode is shear failure under the compression;when the temperature approaches a critical value,the yield stress and the plastic flow stresses are strongly sensitive to temperatures and strain rates.Finally,unlike common metallic materials,this material doesn＇t show obvious aging phenomenon.