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1.
高能球磨法制备纯铝纳米晶材料的研究   总被引:1,自引:0,他引:1  
对应用高能球磨制备纯铝纳米晶材料及其硬度进行了研究分析。结果表明:室温高能球磨可制备纯铝纳米晶材料,球磨12h后平均晶粒尺寸为34nm。纳米晶纯铝的显微硬度随球磨时间的延长先升高后降低,然后趋于稳定。球磨12h制备的纯铝纳米晶材料的硬度最高,可以达到111HV。样品在不同温度下退火后,硬度随温度的升高先升高后下降,并且在200℃退火时发生了低温退火的硬化效应。  相似文献   

2.
采用真空电弧熔炼结合水冷铜模吸铸法制备ZrCuAlNiCoNb大块非晶合金。采用XRD、AFM、SEM及纳米压痕分析手段研究等温退火对ZrCuAlNiCoNb非晶合金显微组织演变、硬度和杨氏模量的影响。结果表明,无论温度高低,退火均能使非晶合金中自由体积的数量减少。在低于玻璃化转变温度下退火,合金中自由体积数量下降,抑制了剪切带的形核,合金的硬度和杨氏模量随退火时间的增加而提高;在高于玻璃化转变温度下退火,短时间即可诱发纳米晶化,合金的硬度和杨氏模量均先增加,达到峰值后下降。ZrCuAlNiCoNb非晶合金力学性能的演变趋势是自由体积演变和纳米晶形核共同作用的结果。  相似文献   

3.
采用FeCrMnMoWBCSi的母合金,通过铜模吸铸法,气雾化方法制备非晶合金粉末,然后用超音速火焰喷涂制作涂层;分别采用不同温度320 ℃、480 ℃与650 ℃在箱式电阻炉内对3组试样进行退火处理制备纳米晶涂层,非晶和纳米晶双物相涂层;SEM电镜观察非晶合金粉末尺寸及形状;经X射线衍射和电化学测试非晶及纳米晶涂层等手段,考察了铁基非晶及纳米晶涂层在NaOH,H2SO4和NaCl溶液中的电化学腐蚀行为.结果表明:导电辊采用铁基HVOF喷涂作为外保护层时,在NaOH碱液采用经非晶退火后的纳米晶为佳,在H2SO4和NaCl溶液中使用时,外保护层可为纳米晶,或为非晶和纳米晶双物相状态皆可.   相似文献   

4.
用正电子湮没多普勒展宽能谱测量和分析了若干急冷淬火制备的薄带,表明软磁Fe基纳米晶合金中的缺陷(自由体积)远多(大)于其晶化前的非晶态;能够晶化成纳米晶的Fe基非晶制备态材料中的缺陷也多(大)于类似成分但又不能晶化成纳米晶的非晶态材料中的缺陷;Fe73.0Cu1.0Nb1.5Mo2.0Si13.5b9.0合金的急冷淬火制备态在热处理过程中,低温退火时缺陷减少,高于200℃的退火导致缺陷增加,纳米晶化后的进一步退火缺陷基本不增加;Fe73.0Cu1.0Nb1.5Mo2.0Si13.5B9.0合金纳米晶化后,在所选定的测量条件下没有发现正电子湮滑参数时间,温度的变化,说明该材料缺陷结构相当稳定。  相似文献   

5.
利用机械合金化工艺制备了颗粒尺寸为0.5μm、W晶粒尺寸为10am的纳米晶W-Cu粉末,研究了其烧结致密化行为、烧结合金显微组织及其性能,并考察了其晶粒长大特性。结果表明:烧结温度和时间的增加有利于致密化,1300℃烧结30min,合金取得了99%的相对密度;硬度随烧结温度、时间的增加而增加,在1375℃烧结30min,硬度为HB321。W晶粒随着烧结温度的升高而增大,1200℃烧结30min获得了相对密度为98%以上、硬度为HB264、晶粒尺寸约为350am的细晶W-Cu合金。  相似文献   

6.
磁控溅射沉积Cu-Nb薄膜的特征及热退火的影响   总被引:1,自引:0,他引:1  
用磁控共溅射法制备含铌1.16%~27.04%(原子分数)的Cu-Nb合金薄膜,运用EDX,XRD,SEM,TEM,显微硬度仪和电阻仪对沉积态和热退火态薄膜的成分、结构和性能进行了研究.结果表明,Nb添加显著影响Cu-Nb合金薄膜微结构,使Cu-Nb薄膜晶粒细化,含铌1.82%~15.75%的Cu-Nb膜呈纳米晶结构,存在Nb在Cu中的fec Cu(Nb)非平衡亚稳过饱和同溶体,固溶度随薄膜Nb浓度增加而上升,最大值为8.33%Nb.随Nb含量增加,薄膜中微晶体尺寸减小,Cu-27.04%Nb膜微结构演变至非晶态.与纯Cu膜对比表明,Nb添加显著提高沉积态Cu-Nb薄膜显微硬度和电阻率,总体上二者随膜Nb含量上升而增高.Nb含量高于4.05%时显微硬度增幅趋缓,非晶Cu-Nb膜硬度低于晶态膜,电阻卒则随铌含量上升而持续增加.经200,400及650℃退火1h后,Cu-Nb膜显微硬度降低、电阻率下降,降幅与退火温度呈正相关.XRD和SEM显示,650℃退火后晶态Cu-Nb膜基体相发生晶粒长大,并出现亚微米级富Cu第二相,非晶Cu-27.04%Nb膜则观察到晶化转变和随后的晶粒生长.Nb添加引起晶粒细化效应以及退火中基体相晶粒度增大是Cu-Nb薄膜微观结构和性能形成及演变的主要原因.  相似文献   

7.
研究了新近开发的纳米晶(Fe90Zr3.5Nb3.5B3)95Cu1Si4合金的微组织和软磁性能.采用XRD、TEM和Mssbauer谱仪观察了合金的微组织变化,采用直流软磁测量设备测量了软磁性能.结果显示,合金是纳米晶相、残余非晶相和中间相的混合.软磁性能随着退火温度的变化而变化,且中间相的体积分数会影响软磁性能.当813K退火0.5h后,纳米晶相体积分数为40%,软磁性能最佳,此时BS最大为1.56T,HC达到最小为1.79A/m.  相似文献   

8.
本文通过对纳米晶软磁合金Fe-Zr-Nb-B磁性能的研究,得知当合金成分配比为Fe85.5Zr2Nb4B8.5且退火40min后合金的磁性能是最佳的。其磁导率为60,000(1kHz),饱和磁感应强度为1.64T,磁致伸缩几乎为零。合金的铁损也很低,在1.4T、50Hz时低至0.09W/kg,这个值比Fe-Si-B系非晶合金要低很多。因此Fe-Zr-Nb-B合金很适合做杆式变压器材料。  相似文献   

9.
本文研究了机械合金化制备的纳米晶WC 10Co复合粉末的真空烧结特征 ,分析了孔隙度、显微硬度随绕结时间延长和烧结温度升高的变化规律 ,考察了一种新型抑制剂的作用。结果表明 :在 132 5℃ / 15min的烧结条件下 ,样品的相对密度达到了 98%以上 ;烧结样品的显微硬度随着烧结时间的延长和烧结温度的升高先增加后降低 ,并且在 132 5℃ / 15min的条件下其硬度为 2 2 95MPa ;新型抑制剂A既有利于晶粒长大的控制 ,同时又有利于材料致密化的进行 ,显著地提高了合金的性能。  相似文献   

10.
采用熔体快淬及晶化退火工艺制备了单相Nd2Fe14B纳米晶合金。研究了添加Nb对Nd12.3Fe81.7-xNbxB6.0(x=0.5,1.0,1.5,2.0,2.5,3.0)系列合金的微观组织、磁性能和晶化行为的影响规律。结果表明:添加Nb可提高晶化温度并稳定非晶相;在退火晶化过程中,加入Nb后形成的析出相可以抑制晶粒长大,使晶粒细化且分布均匀,进而提高了材料的综合磁性能。通过对系列合金磁性能分析可知:Nd12.3Fe81.2Nb0.5B6.0合金在600℃退火处理10min后的磁性能最佳,磁能积(BH)m=141.13kJ.m-3,矫顽力Hci=867.95kA.m-1,剩磁Jr=1.02T。  相似文献   

11.
转炉炉壳热应力分析   总被引:5,自引:1,他引:4  
任学平  郭志强  邹家祥 《炼钢》2001,17(6):47-49
根据实际转炉建立实体模型。以有限元为手段,考虑了炉衬和炉壳材料的物性参数随温度变化的特点和炉衬与炉壳之间膨胀间隙,计算了转炉炉壳在温度载荷和炉衬膨胀压力同时作用下的热应力。所得结果可为转炉炉壳设计提供依据。  相似文献   

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13.
通过对焦炭在高炉内的历程及其变化规律的剖析,阐述焦炭热性能指标的意义,形象地把焦炭在高炉内的损耗分为三部分(M1,M2,M3)。指出M2对焦比及焦炭价格有一定的指导作用。  相似文献   

14.
Cancer of the cardia is traditionally discussed with cardiac cancer of the lower portion of the esophagus and upper gastric cancer invading the esophagus, and the specific characteristics of cancer of the cardia have never been clearly defined. We reviewed the outcome of 172 patients with adenocarcinoma of the cardia who had undergone radical surgery between 1949 and 1994 in the Division of Gastrointestinal Surgery of the Cancer Institute Hospital. The centers of the tumors were located within 2 cm above and below the boundary between the esophagus and the stomach, and their longitudinal diameter was less than 8 cm. We divided the patients into an early period (1949-1979; n = 79) and a late period (1980-1994; n = 93), and focused on the historical transition. There were no differences in patient gender or histology between the two periods. However, the late period was associated with fewer cases of esophageal invasion and shorter longitudinal diameter, as the age of the population advanced. The number of advanced cancers such as the localized and infiltrative type had decreased, and early cancer and early clinical stage had become more common, but despite the fact that the number of early cancers had increased, extended dissection, such as thoracic and paraaortic lymph node dissection, was performed more frequently. By clinical stage, the long-term outcome markedly improved in Stage I patient in the late period, and tended to improve in Stage II and III patients. This appears to have been attributable to the prevention of micrometastasis by extended dissection, although the number of early cancers is another major potential cause. There were no differences in the outcome of Stage IV patients between the two periods, and further advances in multimodality therapy must be awaited. The range of resection is basically proximal gastrectomy, and if there are adequate indications, the prognosis is favorable. In view of the status of lymphatic flow and lymph node metastasis, and long-term results, lateroaortic lymph node dissection is important. Since the number of early cancer patients has been increasing, if intraabdominal recurrence is prevented, intrathoracic lymph node dissection will contribute greatly to the outcome of such patients.  相似文献   

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The effect of 20 different antibiotics on chemotaxis by human neutrophils was studied. Human leukocytes incubated with chloramphenicol, rifampin, sodium fusidate, and tetracyclines in vitro showed markedly depressed migration. The mechanisms by which these antibiotics affect leukotaxis are discussed.  相似文献   

17.
Usage of quality of life of psychiatric patients' relatives as the parameter of estimation of the quality of psychiatric care is considered. By means of standard questionnaire elaborated by the authors as well as by means of both individual and group conversations the quality of life was analyzed in 40 relatives which lived together with psychiatric patients. Different spheres of their life and difficulties (financial, social-psychologic, production) were examined in families with such patients. The defects of psychiatric care that had direct influence on the quality of life of the psychiatric patients' relatives are outlined.  相似文献   

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Some theories of personality hold that an individual's perception of others is influenced by his own personality characteristics; more specifically, that a trait of low social value will be projected more into others, and that insight into the possession of these characteristics reduces this distortion. These 2 hypotheses were tested by having a group of college students rate each other (including themselves) on degree of friendliness or hostility. Agreement with group rating about self yielded the insight score. In general, the hypotheses were supported; the "friendly" Ss were most accurate in their perception of others, and insight was positively associated with accurate perception. From Psyc Abstracts 36:04:4HL16M. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   

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