Hot workability characteristics of Rene88DT superalloy with directionally solidified microstructure

The hot deformation characteristics of Rene88 DT superalloy with directionally solidified microstructure produced by electroslag remelting continuous directionally solidification(ESR-CDSò) were studied in the temperature range of 1,040–1,140 °C and strain rate range of 0.001–1.000 s-1by hot compression tests. Flow curves for Rene88 DT alloy with initial directionally solidified(DS)microstructure exhibit pronounced peak stresses at the early stage of deformation followed by the occurrence of dynamic softening phenomenon. Rene88 DT alloy with DS microstructure shows higher flow peak stresses compared with HIPed P/M superalloy FGH4096, but the disparities in peak stresses between ESR-CDSed Rene88 DT and HIPed P/M superalloy FGH4096 reduce as temperature increases. The improvement of hot workability of DS alloy with columnar grains avoiding the maximum shear stress comes true. A hot deformation constitutive equation as a function of strain that describes the dependence of flow stress on strain rate and temperature is established. Hot deformation apparent activation energy(Q) varies not only with the strain rate and temperature but also with strain. The strain rate sensitivity exponent(m) map is established at the strain of 0.8, which reveals that global dynamic recrystallization(DRX) shows a relatively high m value in a large strain compression.Optimum parameters are predicted in two regions:T = 1,100–1,130 °C,_e = 0.100–1.000 s-1and T = 1,080–1,100 °C,_e = 0.010–0.100 s-1, which is based on processing maps and deformation microstructure observations.     

略论四川电信“十五”期间财务战略构建

国际资本市场电信板块股价雪崩自2000年3月开始，波及全球IT行业持续性的低迷席卷了包括美国VERIZON、日本电报电话公司(NXT)、英国电信(BXY)、德国电信(DT)、法国电信(FTE)、意大利电信(TI)、韩国SK电信(SKM)等在内的众多电信巨头半数以上的市值，而法国电信的市值甚至已经比巅峰时期跌去接近9成。曾经倍受追捧的中国概念股也未能幸免。     

同位素中子源活化瞬发分析装置

一、基本原理自六十年代中期以来,中子活化瞬发γ射线元素分析技术(PNAA)得到人们广泛重视。与通常的中子活化分析(NAA)技术相比,它分析的是样品中的主要成分,若用同位素中子源,还可进行实时在线连续测定及现场分析。PNAA技术是用热中子与待测元素发生中子俘获反应,处于激发态的产物核在瞬间     

国产中子发生器配接引进测井仪成功

本文主要介绍西安石油勘探仪器总厂试制的中子发生器与阿特拉斯公司生产的2727型碳氧比能谱测井仪连配及其成功应用,同时也概括地阐述中子发生器有关特点及使用中应注意的问题。     

用DTA方法测定丁苯胶乳中丁二烯的含量

<正> 一、前言测定丁苯胶乳(SBR)中丁二烯(BD)含量的经典方法是用化学法测定结合的苯乙烯(St)量,再用差减法结算出BD含量。该方法麻烦费时。目前测定SBR中St含量的方法是用乙醇将乳胶凝固,然后再将聚合物溶解,经两次沉淀精制后制得试样,再用阿贝折射仪测定折射率,进而算出St的结合量,但此法处理样品费时,且只能测得St含量,不能直接测出BD含量。国外曾报道采用差示扫描量热技术