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M38镍基高温合金高温低周疲劳性能及断裂机制 总被引:4,自引:0,他引:4
对铸造镍基高温合金M38在900 ℃下的低周疲劳行为进行了研究.采取轴向总应变控制,应变比为-1,应变速率为1×10-2 s-1.实验结果表明:M38在900 ℃下具有与IN738LC接近的疲劳性能.在高应变幅时,疲劳裂纹主要萌生在表面碳化物等应力集中处;在低应变幅时,氧化对裂纹的萌生起重要作用,疲劳裂纹主要萌生于与试样表面相连的易氧化的富Cr晶界处和富Ti的碳化物处.在所有应变幅下,疲劳裂纹均沿垂直应力轴的方向穿晶扩展. 相似文献
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Y.W.Bao Y.C.Zhou 《金属学报(英文版)》2004,17(4):465-470
Creep and stress relaxation behavior, the elastic modulus and fracture toughness of machinable Ti3SiC2 at various temperatures from 20 to 1250℃ were investigated by means of three-point bending tests. The experiments were performed respectively at: (i) fixed stress and changed temperatures, and (ii) fixed temperature and changed stresses. A creep resistance parameter that represents the probability of creep deformation in a given condition was defined as a function of both applied stress and the threshold stress, varying in a range from 0 to 1. Elastic modulus at high temperatures was measured through comparing relative slopes of loading curves in cyclic loading curve. The fracture toughness measured by SENB method showed a stable value in the range of 25-1000℃, but over 1000℃, it declined abruptly from ~6.7MPa.m^1/2 to~2.0MPa.m^1/2 at 1200℃. 相似文献
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低温超声波化学镀镍层的组织结构与性能 总被引:16,自引:1,他引:15
研究了低温(~40℃)超声波化学镀镍层的初期析出行为、组织和相结构,并与常规化学镀镍层进行了比较,结果表明低温超声波化学镀镍层细密均匀,而常规化学镀镍层晶粒粗大且呈不均匀状态,在镀层的横截面上有分层现象。低温超声波化学镀镍层主要为非晶态,夹有少量微晶,而常规化学镀镍层则为典型的非晶态 相似文献
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1. IntroductionThe most promising oxide candidates for the cathode material are lantanum maganitesdoped with strontium belonging to the perovskite family[1--2]. Detailed syllthesis methodsof this ceramic were given in if ie literature by several authors[3--8]. To improve the catalysis,it is necessary to synthesize Lal--.Sr.MnO3 with nanometer-sized powders and very largespecific surface area. In this study3 we synthesized successfully Lal--.Sr.MnO3 compoundwith nanometer-sized powders and … 相似文献
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C.W.Ma F.Z.Xuan Z.D.Wang S.T.Tu 《金属学报(英文版)》2004,17(4):612-617
In this work, a parametric approach is presented and utilized to determine the creep properties of weldments; then the model of creep strain for cross weld specimen is given. On the basis of the experimental results, attempt has been made to establish equations of the isochronous stress-strain for weld joint that can predict the function of loading and service time in use of the creep data of base metal and weld metal. 相似文献
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MECHANICAL PROPERTIES OF Ti3SiC2 AT HIGH TEMPERATURE 总被引:1,自引:0,他引:1
Creep and stress relaxation behavior, the elastic modulus and fracture toughness of machinable Ti3SiC2 at various temperatures from 20 to 1250℃ were investigated by means of three-point bending tests. The experiments were performed respectively at: (i) fixed stress and changed temperatures, and (ii) fixed temperature and changed stresses. A creep resistance parameter that represents the probability of creep deformation in a given condition was defined as a function of both applied stress and the threshold stress, varying in a range from 0 to 1. Elastic modulus at high temperatures was measured through comparing relative slopes of loading curves in cyclic loading curve. The fracture toughness measured by SENB method showed a stable value in the range of 25-1000℃, but over 1000℃, it declined abruptly from -6.7MPa·m1/2 to -2.0MPa·m1/2 at 1200℃. 相似文献
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熔制了14个不同成分的Al-Zn-Cu合金,并进行了组织均匀化和平衡冷却至室温的处理.通过显微组织观察、X射线衍射分析和电子探针微区成分分析,测定了这14个合金的相组成及成分,还通过晶格常数变化和溶质浓度关系的分析,对α与CuZn4相的成分进行了计算,并绘制出了Al-Zn-Cu系低Cu侧的室温相图.结果表明:在室温下Al-Zn-Cu系中存在稳定的化合物T’相,实际确定的室温三相区是:T’ α β,T’ α Al2Cu,T’ CuZn4 β,T’ AlCu Al2Cu.明确了CuZn4中的最高Al含量远远小于原来认知的数值(18%),应该小于7%. 相似文献
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研究了K40S钴基高温合金在700℃和900℃温度条件下由应变控制的高温低周疲劳行为,对疲劳断口形貌进行观察,结果表明;在高温低周疲劳加载条件下,K40S合金疲劳裂纹萌生机制为表面滑移带开裂与表面碳化物相界面开裂的综合作用;疲劳裂纹萌生与扩展方式为穿晶型,瞬断区呈现枝晶断裂特征;碳化物可作为障碍,阻碍疲劳裂纹的扩展,且为主要的二交裂纹策源地;K40S合金高温低周疲劳断裂为机械疲劳与高温环境氧化共同作用的结果。 相似文献
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热解温度对多晶铁纤维的静磁和微波电磁性能的影响 总被引:4,自引:0,他引:4
在气流的诱导作用下,仅通过控制五羰基铁的热解温度,可获得不同晶粒尺寸及化学组成的多晶铁纤维.研究了热解温度对多晶铁纤维的静磁和微波电磁性能的影响规律.结果表明,由于多晶铁纤维的结构和组成随热解温度呈规律性变化,导致多晶铁纤维的静磁和微波电磁性能对热解温度有强烈的依赖性.500℃获得的多晶铁纤维晶粒尺寸为21.6 nm,碳含量为8.26%,此时软磁性能最差,复介电常数和复磁导率最低;而在700℃获得的多晶铁纤维的晶粒尺寸为61.1 nm,碳含量为3.88%,此时具有最佳的软磁性能和最高的介电损耗及磁损耗.这表明通过调节热解温度控制产物的结构和组成,可以获得微波电磁性能优良的多晶铁纤维. 相似文献
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INFLUENCE OF MORPHOLOGY AND DISTRIBUTION OF FERRITE ON FRACTURE BEHAVIOR OF LOW-CARBON STEEL AT LOW TEMPERATURE 总被引:1,自引:0,他引:1
本文根据轧后控制冷却过程中,16MnR钢组织和性能的变化规律,着重讨论了魏氏组织中,针形铁素体分布状态对低碳钢低温韧性的影响。试验及分析结果表明,与块状铁素体组织相比,魏氏组织中针形铁素体的影响,主要取决于针形铁素体的分布状态.交叉分布针形铁素体组织具有较优越的抗冷脆性能;而平行排列针形铁索体则会使钢的低温韧性恶化。 相似文献
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TiAl基合金显微组织对高温拉伸力学性能的影响 总被引:5,自引:3,他引:5
研究了TiAl基合金不同显微组织试样在900℃下的拉伸力学性能。试验结果表明,在晶粒尺寸相当的前提下,与双态组织相比,细小层片状组织试样表现出良好的高温综合力学性能。采用光学金相显微镜,SEM和TEM等检测分析仪器,详细地对试样拉伸前后的显微组织进行了分析研究 相似文献
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Sm2Co17基高温稀土永磁材料的显微结构与磁性 总被引:4,自引:0,他引:4
Cu含量较高的Sm2Co17基永磁材料在高温下具有较大的内禀矫顽力,而Fe含量较高时其高温下的磁性较差.TEM显示磁体由胞状结构构成,胞内为2:17R相,胞壁为1:5相,在MFM(磁力显微镜)下可观测到片状相(1:7相),畴结构为波纹畴和条状畴,但是在片状相出现的区域并未观察到畴壁钉扎点,而在胞壁相的三角结合区域畴壁的钉扎强度最高,高温X射线衍射分析表明,随着性能的降低观测到材料的相结构发生了较大的变化,由室温下的2:17R主相、1:5相和1:7相变为非晶结构,且最终转变成700℃时的SmCo3主相和2:17R相,相结构的转变直接导致磁体性能的降低。 相似文献
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用射频溅射法制备了非晶态CoZr合金薄膜,在0.5Pa的氩气压下,可以得到性能优良的软磁薄膜。研究了非晶态CoZr膜的饱和磁化强度与Zr含量及温度的关系,发现对各种成分的非晶态CoZr膜,在很宽的温度范围内都可满足Bloch T~(3/2)定律。根据刚带模型计算出每个Zr原子向Co的3d能带转移的电荷数约为2.27。 相似文献