机械球磨过程中Mo-37.5%Si混和粉晶粒尺寸和微观应变的研究

采用多重峰和双峰分离技术及计算机软件包,成功地进行了单一Mo峰的分离,测定和计算了球磨过程中粉末晶粒尺寸和晶格畸变随球磨时间的变化。随着球磨时间的延长,Mo-37.5％Si(原子分数)混合粉中的Mo粉晶粒尺寸减小,但变化速度减缓。经过15h的球磨后,可以得到纳米级合金粉末,经80h球磨后,晶粒尺寸下降到约7.6nm。另一方面,球磨造成的微观应变不大。     

高能球磨制备纳米晶镁合金粉末的研究

利用氩气保护下的高能球磨,制备了纳米晶AZ31镁合金粉末。采用X射线衍射(XRD)、扫描电镜(SEM)和透射电镜(TEM)等方法,研究了高能球磨过程中粉末微观组织与形貌演变规律。结果表明:随着球磨时间的延长,镁合金粉末的晶粒尺寸逐渐减小,微观应变和晶格常数逐渐增大;粉末颗粒首先被碾压成扁平状并相互焊合使颗粒尺寸粗化,然后随球磨的继续进行发生断裂,使颗粒尺寸逐渐减小;球磨80h后,粉末组织与形貌均趋于稳定,获得了平均颗粒尺寸为15～20μm、晶粒尺寸为85nm左右的纳米晶AZ31镁合金粉末。     

机械合金化诱导难互溶系Cu-Cr合金固溶度扩展的研究

采用机械合金化工艺制备Cu-4%Cr和Cu-7%Cr(原子分数)二元合金粉末,利用XRD,SEM和TEM研究机械合金化过程中粉末的微观形貌和显微组织结构,测量了不同球磨时间粉末的氧含量以及显微硬度.结果表明:在一定的球磨时间内,Cu-Cr合金粉末随着高能球磨的进行,晶粒逐渐细化至纳米尺寸,晶格畸变增加,但进一步球磨会导致铜的晶格常数有所增加,畸变降低.实验证明,在固态下几乎不互溶的Cu-Cr合金,经球磨40 h的机械合金化,Cr在Cu中的固溶度明显提高.     

机械球磨法制备纳米晶复相Nd2Fe14B/α-Fe永磁粉末

通过将成分为Nd2Fe14B（原子比）的铸态合金与羰基铁粉的混合粉末进行搅拌式机械球磨，并对球磨后的合金粉末进行真空晶化处理，制备了纳米复相Nd2Fe14B/α-Fe永磁合金。通过X射线衍射（XRD）、差示扫描量热法（DSC）、透射电子显微镜（TEM）等分析方法研究了球磨时间及晶化处理温度对合金微观组织的影响。结果表明，随球磨时间的延长，Nd2Fe14相及α-Fe的晶粒尺寸迅速减小，球磨5h后粉末由Nd2Fe14B非晶相和晶粒尺寸约为10nm左右的α-Fe组成，在随后的晶化热处理过程中转变成Nd2Fe14B／α-Fe纳米复相组织。     

球磨时间对W-30Cu复合粉末中W晶粒度及烧结致密化行为的影响

研究了高能球磨时间对W-30Cu复合粉末晶粒度及烧结行为的影响.结果表明,当球磨时间从16h提高到33h时,复合粉的晶粒度由25nm减小到10nm,并发生机械合金化现象;在温度为1275℃烧结60min,经18h高能球磨的复合粉末烧结就可以达到全致密.研究还发现,高能球磨W-30Cu复合粉末具有较好的热稳定性,经950℃退火处理,晶粒尺寸没有发生异常长大现象;经烧结材料的硬度明显高于普通的W-30Cu复合材料.经1 275℃烧结30 min后合金其晶粒尺寸在300～550 nm.     

热机械合金化法制备纳米晶W-Cu复合粉末

采用热机械合金化制备纳米晶W-Cu复合粉末。通过XRD、SEM、激光粒度测试等方法对球磨后的粉末进行表征。结果表明:随球磨时间延长,W的晶粒尺寸不断减小,球磨30 h后W的平均晶粒尺寸为41 nm左右;球磨初期,粉末迅速细化;随球磨时间延长,粉末粒度有所增加;进一步增加球磨时间,粉末粒度减小。球磨粉末还原后有较高的烧结活性,1 200℃烧结后相对密度可达97%以上。烧结材料的组织非常均匀,且晶粒细小。     

高能球磨时间对W-Cu纳米晶复合粉体组织和性能的影响

采用机械合金化法制备W-20％Cu(质量分数)纳米晶复合粉体.通过XRD,SEM等方法对球磨后的复合粉体进行表征,研究球磨时间对复合粉体的物相成分、晶粒尺寸、微观应变以及表面形貌的影响,并探讨机械合金化过程中过饱和固溶体的形成机制.结果表明:随着球磨时间的延长,W的晶粒尺寸及晶格常数不断减小,微观应变逐渐增大；球磨40...     

Mo-Si-B基超高温合金粉体的机械合金化

采用XRD,SEM和EPMA等方法分析Mo-12Si-10B-3Zr-0.3Y(原子分数)混合粉末在500 r/min转速下进行球磨时的机械合金化行为。结果表明:球磨后在混合粉末中并未形成Mo3Si和Mo5SiB2化合物相,而仅形成了合金元素在Mo中的过饱和固溶体Moss和弥散分布于其中的亚微米级B颗粒。随球磨时间延长,Moss的晶粒尺寸不断减小,其微观应变不断增加,球磨30 h后两者分别约为47 nm和0.53%;从XRD谱可知,球磨2 h后有少量的α-MoSi2生成,但球磨30 h后其衍射峰消失。球磨5 h后混合粉末由层片状的复合颗粒组成,球磨10 h后层片状复合颗粒破裂并转变为等轴状,球磨30 h后混合粉末由平均粒径约1μm的球状团聚体颗粒组成。     

纳米稀土硬质合金原料粉末的制备及研究

采用高能球磨法制备出了用于生产纳米晶稀土硬质合金的原料粉末。通过XRD、SEM和DTA等分析检测手段，研究了该纳米WC—Co—RE粉末的结构、形貌和相的变化。结果表明：高能球磨45h，可获得晶粒尺寸约为8．45mm的WC—Co—RE粉末；微量稀土的加入，有利于粉末晶粒的细化；在25～45h范围内，随着高能球磨时间的延长，粉末晶粒尺寸的减小趋势符合直线变化规律，且掺稀土粉末的晶粒尺寸比未掺稀土粉末的晶粒尺寸减小一半；高能球磨25h，粉末中Co相的X射线衍射峰消失。高能球磨ⅥE—Co—RE粉末的DTA曲线在597℃出现了一个尖锐的放热峰。高能球磨WC—Co—RE粉末固结之后，所制得合金的晶粒细小且机械性能较好。     

球磨时间对Al2O3/Mo复合材料组织与性能的影响

采用溶胶-凝胶法制备Al2O3/Mo混合粉体,利用高能球磨法细化Al2O3/Mo复合材料中氧化铝和钼的晶粒尺寸,研究了球磨时间对Al2O3/Mo复合材料组织与性能的影响,利用XRD和扫描电镜对复合粉末形貌和复合材料进行了物相和形貌分析。研究表明:随着球磨时间的延长,复合粉末的形貌经历了球状到层片状再到球状的变化,粉末粒度逐渐减小,经粉末冶金烧结后的复合材料中,氧化铝和钼的粒径逐渐减小,经过60h的球磨,氧化铝颗粒的尺寸达到500nm左右;复合材料的密度呈现先增加后减小的趋势,显微硬度则逐渐上升至403.2HV。     

转炉炉壳热应力分析

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。     

The effect of amount of possession of the trait of hostility on accuracy of perception of hostility in others.

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)     

Comparison of rates of infection of two methods of emergency ventricular drainage

The rates of infection of two methods of external ventricular drainage in use at Atkinson Morley's Hospital--namely, (a) percutaneous drainage with Rickham reservoirs and (b) tunnelled ventriculostomies--were compared in this retrospective review. Percutaneous drainage of CSF with Rickham reservoirs was associated with a 27% rate of infection as identified by positive microbiological cultures; tunnelled ventriculostomy catheters had a 10% infection rate. The difference in the infection rate between the two methods was statistically significant (P < 0.015). Other variables examined, including the age and sex of the patients and the reasons for ventricular drainage, were not associated with an increased rate of infection. Most infections from either method were caused by a coagulase negative staphylococcus. The average duration of ventricular drainage before identification of positive cultures was 5.7 days for Rickham reservoirs and 6.0 days for ventriculostomies.     

浅析《野草》的版画特征

鲁迅先生一生热爱美术作品,对版画中木刻兴趣尤甚.<野草>作为其"写心之作",亦呈现出一些与木刻版画一致的审美特征:一是具有木刻版画的色彩特征,多对比、多冷色,有阴郁的美感;二是具有木刻版画的力度特征,环境描写、人物刻画处处刀锋毕现,遒劲有力,有一种"力之美".     

四辊破碎机车刀架的改造

针对四辊破碎机车刀架车削中存在的几个问题,详细介绍了电动车刀架的结构和工作原理,建立主要设计参数的数学表达式,并进行适当的分析。改造后,这种电动车刀架运行平稳、可靠、方便、省力,取得了预期的效果。     

焦炭热性能指标意义浅析

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。     

Results of treatment of cancer of the cardia

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.     

Comparison of the results of surgical and conservative treatment of fractures of the diaphysis of the tibia

In this paper is treated the fundamental problematic of the fracture of the diaphysis of the tibia and the therapeutic results after the conservative and operative treatment are confronted. Among 518 patients with 433 open fractures and 35 with closed fractures of the diaphysis of the tibia, successful treatment of more 2/3 was obtained in the period from 1968 to 1972. Following our casuistics and literature, whose results are similar, we find out that the average total treatment of the osteosynthesis of the fracture of the diaphysis was shortened for 2,5 months depending upon the type and the localisation of the fracture. Apolied methods of the operative and conservative and conservative treatment in relation to the velocity of the medical cure as well as to the extreme anatomical-functional results are analised. We noticed that osteosynthesis, made by the intermedullary nail and the extension of the canals or by a small AO table, by the achieved stability makes conditions of immediate motions and an early rehabilitation. Because of that it gives the best functional results.