时效工艺对6061铝合金力学性能各向异性的影响及微观组织研究

采用单向拉伸试验研究了经不同时效工艺处理的6061铝合金轧制板材在轧制方向(0°)、倾斜方向(45°)和横向(90°)的力学性能各向异性.实验结果表明,轧制态6061铝合金的力学性能与热处理工艺密切相关,且表现出明显的各向异性.其中T6态6061铝合金力学性能各向异性最不明显.轧制态6061-T6铝合金有较强的立方织构{001}〈100〉和较弱的织构成分{001}〈100〉,目前采用的人工时效方法对其晶粒的显微组织和织构演化的影响不大.相对于经其他工艺处理的轧制态6061铝合金,经240℃高温时效处理的轧制态6061-T6铝合金位错密度大,且分布更均匀.轧制态6061-T6铝合金中明显的高密度β″析出物是其具备最高强度和最低各向异性的主要原因.     

LY12铝合金的再结晶织构及晶界特征分布

利用X射线定量织构分析术和背散射电子衍射花样术,研究了冷轧LY12铝合金的再结晶织构及重位(CSL)晶界的分布.结果表明,高温退火样品的再结晶织构与冷轧样品的织构相似;预回复低温退火具有增强再结晶立方{001}〈100〉织构和降低退火S{123}〈634〉、C{112}〈111〉及B{110}}〈112〉织构组分的作用;高强度的再结晶立方织构和一定强度的S织构共存的样品,∑7重位晶界具有较高的出现频度.     

Cu-Cr-Zr系合金变形过程中的织构分析

对Cu-Cr-Zr系合金铸锭进行热轧、固溶和冷轧,利用X射线衍射仪测试合金材料不同状态下的织构,分析各个状态下的织构种类及其演变规律.结果表明:热轧后材料中主要织构为Copper{112}〈111〉(C)织构、Brass{011}〈211〉(B)织构和S{123}〈634〉织构,存在微弱的立方织构{001}〈100〉;固溶后材料中织构的强度降低,立方织构消失;冷轧后材料中织构的强度随着变形量的增加而强度增加,冷轧过程中主要织构也是C织构、B织构和S织构,在冷轧初期出现Goss{011}〈100〉(G)织构,随后G织构慢慢减弱,直至消失.     

铸辗成形环坯热压缩过程中晶粒的取向和织构演变

在不同变形温度和应变速率为0.1 s-1条件下研究了砂型铸造和离心铸造Q235B环坯的热压缩变形行为,并使用电子背散射衍射(EBSD)技术分析其晶粒取向和织构的演化特点。结果表明:Q235B环坯的晶粒在1000℃尺寸较小,有少量仍保持铸造状态的晶粒,组织演变的机理为动态回复和大应变几何动态再结晶;离心铸造环坯中有22%集中在20°-50°的大角度晶界。在1100℃再结晶充分,晶粒趋于等轴状;晶界取向差分布仍呈现典型的双峰特征,大角度晶界的比例为60%-75%。在1000℃砂型铸造Q235B的织构组态,为少量沿着001//ND取向线分布的{001}100立方织构和{001}110织构;在1100℃主要是高斯织构{110}001和沿着110//ND向{110}001方向移动并聚集的旋转立方织构{110}110。在1000℃离心铸造环坯的织构组态为旋转立方织构{110}110和铜型织构{112}111,Copper织构沿着ε-取向线分布;在1100℃主要为{001}110织构和沿着γ取向线由黄铜R{111}112向{111}110转变的织构,再结晶的程度高,取向密度大。     

冷轧形变量对异步轧制高纯铝箔织构的影响

应用取向分布函数(ODF)研究和分析了异步轧制高纯铝箔的形变织构和再结晶织构.结果表明:异步轧制高纯铝箔的形变织构除了C{112}<111>、B{110}<112>和S{123}<634>织构组分外,还有较强的CubeND{001}<110>和{102}织构.异步轧制高纯铝箔的再结晶织构由强的立方织构{001}<100>和弱的R{124}<211>织构组成.随着形变量的增加,异步轧制高纯铝箔的形变织构和再结晶织构呈现规律性的变化,{102}织构减少,S织构先增后减,速比较小时C织构近线性减少,速比较大时C织构则先增后减.异步轧制高纯铝箔的退火样品中有很强的立方织构,这与异步轧制提高高纯铝箔的形变储能有关,形变量过大时,立方织构随形变量的增加急剧减少.{102}织构有利于再结晶立方织构的加强.     

高硅钢薄板退火过程中的织构演变

采用传统的轧制和退火工艺制备了0.30mm厚的6.5%（质量分数）Si高硅电工钢薄板,采用X射线衍射技术对退火过程中的再结晶织构进行了研究。冷轧高硅钢薄板700℃退火形成以{111}〈112〉为峰值的γ织构（〈111〉∥ND）和以{001}〈210〉为峰值的{001}织构;而900℃以上温度退火则形成强{001}〈210〉织构。进一步的研究表明是在晶粒长大过程中{001}〈210〉发展成为主要再结晶织构组分。     

3104铝合金再结晶织构的研究

应用取向分布函数(ODF)研究和分析了3104铝合金经不同工艺退火后的再结晶织构.结果表明:3104铝合金,形变织构由C{112}〈111〉,B{110}〈112〉,S{123}〈634〉织构组分组成;退火温度和保温时间对3104铝合金再结晶织构有重要影响,在低温短时退火时立方织构取向密度较弱,但随温度升高和保温时间的延长,立方织构取向密度逐渐增加,在经350℃60min,400℃60min和450℃15min等温退火后,再结晶基本完成,立方织构取向密度在400℃保温60min退火时达到最大,约为10级,但仍保留有少量冷轧织构;随着退火温度的升高,第二相粒子Al6(Fe,Mn)和Al(Fe,Mn)Si在再结晶过程中起到了粒子促进形核作用(PSN).     

冷轧Al_(0.3)CoCrFeNi高熵合金退火再结晶组织和织构的演变

利用维氏硬度计(HV)、X射线衍射仪(XRD)、电子背散射衍射(EBSD)和透射电镜(TEM),研究了90%冷轧Al0.3CoCrFeNi高熵合金在900℃退火过程中的微观组织和织构演变规律。结果表明:退火0.5h合金发生完全再结晶,退火孪晶形成于再结晶面心立方(FCC)晶粒内;经退火1h后,富集Al-Ni原子的有序体心立方(BCC)相优先于FCC相的晶界处形核,且FCC相和BCC相均随着退火时间(1h~10h)的延长而发生晶粒长大。再结晶FCC相的织构组分主要为强{123},〈634〉S织构和强α-{110}纤维织构,{001}〈100〉立方织构随着退火时间的延长也逐渐转化为强织构;再结晶过程的进行使无择优取向的初始BCC晶核选择性长大,{111}〈112〉织构从而演变为强BCC相织构。     

Al-Zn-Mg-Cu系铝合金厚板冷轧过程中的织构演变

利用电子背散射衍射技术研究了Al-Zn-Mg-Cu系铝合金厚板冷轧过程中不同厚度处的织构演变.结果表明:厚板近表面处的剪切型织构{001}<110>,随着冷轧变形量的增加逐渐向轧制型织构Bs,S,Cu组分转变;厚板1/4厚度和中心厚度处的轧制型织构Bs,S,Cu组分,随着冷轧变形量的增加逐渐流向剪切型织构{001}<1...     

轧制方式对6016铝合金薄板组织和塑性各向异性的影响EI北大核心CSCD

利用凸耳实验、X射线衍射仪、EBSD等手段研究了热轧退火后常规轧制(NR)、横向轧制(TR)、交叉轧制(AR)等轧制方式对6016铝合金组织和平面各向异性的影响。结果表明:热轧退火后6016铝合金形成了强烈的立方织构{100}〈001〉。NR,TR冷轧板具有38%~44%的β取向线织构(主要包括铜,S,黄铜织构组分),但是AR冷轧后保留了12.2%的立方织构组分,变形织构组分很弱,因此AR冷轧板材制耳率最差,为7.1%。6016铝合金经过固溶处理后,NR,TR板形成9.12%强烈的立方织构,AR板的织构明显弱化且随机分布,因而AR再结晶退火板制耳率较NR,TR板的6%~8.16%明显降低,为2.76%。固溶处理后6016铝合金板的平均晶粒尺寸分别为23,25,22μm,AR轧制后合金的晶粒最小且分布最均匀。因此交叉轧制能有效改善6016铝合金板再结晶退火后的组织均匀性和塑性各向异性。     

Estimation of Parameters of Universal Distribution of Moments of Failure of Products

A method is proposed for estimating the parameters of a mixture of exponential and Weibull distributions for which the accuracy of preliminary estimates obtained by graphical analysis is refined in accordance with the criterion of maximum likelihood. The efficiency of the proposed method is supported by the results of statistical modeling.     

Assessment of intakes of mixtures of radionuclides

Australia has several uranium mines and a large number of mineral sand mines, with associated processing facilities. Exposures resulting from these mining and processing operations usually involve intakes of mixtures of radionuclides. This work describes the development of a suite of first order, linear compartment models, based on the ICRP Publication 66 respiratory tract model, and an analytical solution to the decay equations, for assessing the consequences of such intakes. The computer programs based on these models directly compute excretion, organ retention and organ and whole-body doses for intakes of either single radionuclides or any mixture of radionuclides belonging to the same radioactive decay chain. The intake can be via inhalation, ingestion or injection, and can be acute, chronic or of limited duration. The starting concentration and degree of secular (dis)equilibrium can be specified for each radionuclide. No assumptions need to be made about the relative magnitudes of the radioactive half-lives of the different nuclides.     

卧式金属罐容量的测量结果不确定度

本文根据多年的实践检定经验 ,参照JJF1 0 59- 1 999《测量不确定度评定与表示》以及《测量不确定度表达 1 0讲》 ,对卧式金属罐容量的测量结果不确定度进行了评定。     

盐酸浓度不确定度的评估

通过对盐酸浓度标定的过程分析，找出影响结果的各个分量，进行不确定度的评定，按照计量技术规范给出标准的表示法。     

Evaluation of optical properties of highly scattering media by moments of distributions of times of flight of photons

A novel method for the determination of the optical properties of tissue from time-domain measurements is presented. The data analysis is based on the evaluation of the first moment and the second centralized moment, i.e., the mean time of flight and the variance of the measured distribution of times of flight (DTOF) of photons injected by short (picosecond) laser pulses. Analytical expressions are derived for calculation of absorption and of reduced scattering coefficients from these moments by application of diffusion theory for infinite and semi-infinite homogeneous media. The proposed method was tested on experimental data obtained with phantoms, and results for absorption and reduced scattering coefficients obtained by the proposed method are compared with those obtained by fitting of the same data with analytical solutions of the diffusion equation. Furthermore, the accuracy of the moment analysis was investigated for a range of integration limits of the DTOF. The moment analysis may serve as a comparatively fast method for evaluating optical properties with sufficient accuracy and can be used, e.g., for on-line monitoring of optical properties of biological tissue.     

Analysis of anisotropy of properties on the basis of studies of texture of coarse-grained ingots of thermoelectric materials

An analysis of anisotropy of the properties of a Bi₂Se_0.3Te_2.7 solid solution was carried out using construction of demonstrative surfaces for thermoelectric effectiveness and thermal expansion coefficients. It is shown that the texture is an important factor forming anisotropy of properties and technological fitness of ingots for manufacturing modules. Anisotropy of properties based on the studies of the ingot textures obtained using the float-zone method and Bridgman method (growing thermoelectric plates in a flat cavity) was studied.     

Analysis of the rate of propagation of the wave of change of boiling modes

An approximate analytical expression is derived for the velocity of the front of the wave of change of boiling modes on a rod and on a plate. The impact of the Thomson effect and of the heater orientation in the gravity field is included. Adequate agreement is demonstrated between the derived relations and experimental data.