CAJ | 학술논문

采用 X 射线衍射(XRD),扫描电镜(SEM)及能谱(EDAX)等方法,研究了 Cr5．0 Co8．0 Mo0．9 W5．5 Ta7．4 Al6．0 Re4．2合金在900和1000℃的氧化行为.结果表明,氧化动力学曲线遵循氧化初期氧化增重速率较快,氧化期间氧化动力学曲线呈波浪式变化,且呈现氧化温度越高波浪式越明显的特征.在900℃氧化300 h 后合金表面氧化物膜分为3层,外层为 NiO、Ni2 Cr2 O 4、Ni2 CoO 4和 CrTaO 4；中间层为平直的Al2 O 3层,内氧化层为Al2 O 3,氧化期间,分布在外层的 CrTaO 4抑制基体中 Al 向外扩散,并抑制氧化膜的生长,使氧化速度降低.1000℃时合金表面的氧化物膜分为2层,外层为 NiO、Ni2 Cr2 O 4、Ni2 CoO 4和CrTaO 4；内氧化层为 Al2 O 3.在900和1000℃氧化期间,合金均发生元素 Al 的内氧化和内氮化,与外氧化膜相邻的区域为元素 Al 的内氧化区,远离外氧化膜的基体内部形成元素 Al 的内氮化区,随氧化温度升高,内氧化区和内氮化区的深度增加,内氧化物和内氮化物的尺寸增大.
채용 X 사선연사(XRD),소묘전경(SEM)급능보(EDAX)등방법,연구료 Cr5．0 Co8．0 Mo0．9 W5．5 Ta7．4 Al6．0 Re4．2합금재900화1000℃적양화행위.결과표명,양화동역학곡선준순양화초기양화증중속솔교쾌,양화기간양화동역학곡선정파랑식변화,차정현양화온도월고파랑식월명현적특정.재900℃양화300 h 후합금표면양화물막분위3층,외층위 NiO、Ni2 Cr2 O 4、Ni2 CoO 4화 CrTaO 4；중간층위평직적Al2 O 3층,내양화층위Al2 O 3,양화기간,분포재외층적 CrTaO 4억제기체중 Al 향외확산,병억제양화막적생장,사양화속도강저.1000℃시합금표면적양화물막분위2층,외층위 NiO、Ni2 Cr2 O 4、Ni2 CoO 4화CrTaO 4；내양화층위 Al2 O 3.재900화1000℃양화기간,합금균발생원소 Al 적내양화화내담화,여외양화막상린적구역위원소 Al 적내양화구,원리외양화막적기체내부형성원소 Al 적내담화구,수양화온도승고,내양화구화내담화구적심도증가,내양화물화내담화물적척촌증대.
The oxidation behaviour of Cr5.0 Co8.0 Mo0.9 W5.5 Ta7.4 Al6.0 Re4.2 superalloy at 900 and 1 000 ℃in air has been investigated by means of measuring the kinetics curves of the oxidation and analysis method of TGA,XRD and SEM/EDAX.Results show that the oxidation initial oxidation rate is rapid,with the oxidation time,the increasing of oxidation weight overall tends to be smooth,but the oxidation kinetics curve for superal-loy later has a wavy change and obviously for the higher oxidation temperature.The oxidation film are consist of three layers at 900 ℃.The outer layer is mainly composed of NiO,Ni2 Cr2 O 4 ,Ni2 CoO 4 ,CrTaO 4 and continuous middle layer and disconnected inner layer of Al2 O 3 .The phase CrTaO 4 decreases the diffusion rate of Al.As a result,a continuous oxide layer of Al2 O 3 is formed in the middle layer to restrain the growth of oxide film and decrease the oxidation rate.The oxidation film are consist of two layers at 1 000 ℃.The outer layer is mainly composed of NiO,Ni2 Cr2 O 4 ,Ni2 CoO 4 ,CrTaO 4 ,and disconnected inner layer of Al2 O 3 .The internal oxide (Al2 O 3 )and internal nitride(AlN)precipitates formed inside the superalloy after exposure for 300h during oxi-dation at 900 ℃ and 1 000 ℃;the internal oxidation zone forms on the near-surface area of the superalloy,in-ternal nitridation zone forms below the internal oxidation zone inside the superalloy;with the increasing of tem-perature the internal oxidation zone and internal nitridation zone are wider,simultaneity the size of internal ni-tride and internal oxide increase.