均质化制度对Mg-Li合金显微组织和机械性能的影响

研究了超轻镁锂变形合金热处理后的合金显微组织和机械性能。镁锂合金在室温条件下具有非常良好的延展性，Mg—Li—Zn系变形镁合金铸锭经不同温度、时间均匀化退火后的组织、硬度以及冷轧性能进行了研究。结果表明。Mg．9％Li-2％Zn-2％Ca合金在573K温度均匀化退火12h后合金铸锭组织均匀；而对于Mg-9％Li-2％Zn合金，523K温度均匀化退火24h后组织较好。     

冷轧率与退火工艺对汽车用5754铝合金组织演变的影响

本文研究了汽车结构件用5754铝合金经不同冷轧变形量(冷轧率58%～75%,对应厚度2.5 mm、2.0 mm及1.5 mm)后再进行H22、H111两种退火处理的整个生产过程中组织的演化。在冷轧变形以及后续退火过程中,5754合金中等效圆直径大于0.2 μm的第二相分布不再发生改变,与热轧状态完全一致。热轧板芯部相比表层具有更多的轧制织构,存在沿厚度方向上的不均匀性。2.5 mm厚5754铝合金在冷轧和H22状态下也存在组织不均匀性。然而不同的是,冷轧后,铝合金表层轧制织构增多;在不完全退火时,这种不均匀的方式再一次发生改变,芯部依然存在大量轧制织构,而表层的再结晶程度更高,立方织构明显增多;H111状态完全再结晶退火后,板材表层和芯部组织趋于均匀。随着冷轧率的增加,2.0 mm及1.5 mm厚的板材组织较为均匀,冷轧及H22、H111退火状态板材均未出现表层与芯部的组织差异。冷轧后,板材组织呈纤维状,立方织构较热轧板进一步减少;H22不完全再结晶退火状态时,可以观察到板材发生部分再结晶,轧制织构减少,立方织构增多;至H111完全再结晶状态时,组织呈等轴晶状,立方织构达到最大值。     

退火工艺对 AZ61镁合金铸坯组织及加工性能的影响

研究了均匀化退火对AZ61半连续铸锭的组织及变形性能的影响.通过组织观察、显微硬度测量以及在1500D Gleeble实验机上进行热压缩并计算变形能,分析比较了均匀化温度和时间对坯料组织和变形性能的影响.结果表明:均匀化退火有利于消除铸态组织中的枝晶偏析,不同均匀化退火工艺对第二相化合物的存在方式存在影响;AZ61镁合金硬度值随着退火温度的升高呈降低趋势;退火温度越高,AZ61镁合金热变形峰值应力大小随保温时间的波动逐渐变大;AZ61镁合金优化的退火工艺参数为400 ℃×12 h.     

TA5合金板材工艺对显微组织和力学性能的影响

研究了TA5合金板材的加工、退火及热矫形工艺对组织和力学性能的影响。结果表明:板坯第2火次锻造在相变点以上150℃变形,造成板材组织粗化,呈纤维状,强度非常高,塑性变化不大;换向轧制的板材组织均匀等轴化,再结晶晶粒尺寸增加,强度显著降低,塑性明显升高;随着精轧温度的升高,再结晶晶粒均匀化长大趋势明显,板材强度降低,塑性升高;为了避免热矫形过程对板材组织性能的影响,退火温度应高于热矫形过程中的料温;板材经过二次或三次热矫形后,不平度可达到(2~3) mm/m,室温力学性能基本不变。      

AZ10镁合金均匀化退火工艺研究

通过金相组织分析、显微硬度测试和热压缩实验,研究了不同退火温度和时间条件下AZ10镁合金铸坯的显微组织、显微硬度、热压缩变形抗力以及变形能,分析了退火温度和时间对铸坯组织转变、成分均匀化、变形抗力和变形能的影响.结果表明,退火温度对均匀化起主要作用,AZ10镁合金铸锭的均匀化退火的优化工艺为400 ℃×18 h.     

立方织构Ni-Cr-Mo-W合金薄带及其性能

为了得到高份额立方织构金属基带,同时兼顾居里温度和屈服强度的要求,设计了Ni-7.8%Cr-1.1%Mo-1.6%W(原子分数)合金。采用冷坩埚悬浮熔炼技术冶炼合金铸锭,铸锭经过锻造、热轧、冷轧和再结晶退火,最终得到厚度为100μm的合金薄带。采用电子背散射衍射(EBSD)技术对合金薄带再结晶织构进行了表征,并研究了其磁性能及力学性能。结果表明:经大变形量冷轧和优化的两步法退火后Ni-7.8%Cr-1.1%Mo-1.6%W合金薄带立方织构份额为93.4%,小角晶界体积分数为84.5%;合金薄带的居里温度为25K,远低于77K;合金薄带室温下的屈服强度为182 MPa,与Ni-5%W合金相当,且抗拉性能十分优异。     

超高纯银静态再结晶组织演变规律的研究

采用超高纯银(纯度高于99.999%)铸锭,通过轧制变形,结合后续不同热处理工艺,研究了变形量、退火温度及时间对超高纯银回复及再结晶组织的影响。结果表明:超高纯银的再结晶温度非常低,在100℃时保温5min后即发生再结晶,并且再结晶速度快,在200℃下保温5min即完成再结晶。随轧制总变形量增加晶粒尺寸变小,均匀性提高,当变形量大于等于85%时,可以得到均匀、细化的再结晶组织;超高纯银的最佳再结晶温度应控制在150℃,时间为1~2h之间。     

ECAP变形对Mg2Si增强耐热镁合金组织及性能的影响

为了提高镁合金的耐热性能,在Mg-Zn合金中加入Si,形成Mg-Zn-Si镁合金.采用ECAP工艺在变形温度为573 K和挤压路径为Bc条件下对Mg-Zn-Si镁合金进行不同道次的变形.运用金相显微镜(OM)、X射线衍射仪(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)等手段对变形后的Mg-Zn-Si镁合金进行了组织表征,对变形后的合金进行了室温拉伸和高温蠕变等力学性能测试.结果表明:随着挤压道次增加,α-Mg基体、Mg Zn相及Mg2Si相均得到细化且分布趋于均匀.1道次挤压后部分基体α-Mg细化,4道次挤压后α-Mg的尺寸减小为5~10μm,且晶粒大小趋于均匀;2道次挤压后Mg2Si相枝晶在原位置破碎为颗粒状,6、8道次挤压后Mg_2Si相呈弥散分布.4道次挤压后合金的屈服强度和抗拉强度均提高120%,伸长率提高353%;8道次挤压后合金的抗拉强度和伸长率与4道次相比变化不大,但屈服强度进一步提高了19%.随着挤压道次增加,高温抗蠕变性能提高,8道次后高温稳态蠕变速率降低5倍.Mg2Si相细化机理为受剪切而机械碎断.     

挤压态定向凝固镁合金组织及力学性能

采用自行设计制造的定向凝固设备,制备了大直径镁合金铸锭,并采用金相显微镜(OM)、扫描电子显微镜(SEM)和室温力学性能测试等手段,研究了合金元素、挤压温度和挤压比对挤压态定向凝固镁合金金相组织和力学性能的影响。研究结果表明:对于Mg-Al系二元合金,随着Al元素在0.2%～1%的范围内增加,挤压态定向凝固镁合金的强度和延伸率都逐渐增大,但Al元素的增加也导致了组织均匀化程度的降低。较低的挤压温度和较高的挤压比有利于定向凝固AZ31获得较均匀的再结晶晶粒和第二相,因此当挤压温度为623K,挤压比为80时,挤压态定向凝固AZ31合金的屈服强度、抗拉强度和延伸率分别为255MPa、312MPa和18%,具有较优良的综合室温力学性能。     

Al含量及均匀化处理对AZ系列镁合金组织的影响

为了在挤压生产中获取均匀的镁合金变形组织,需要掌握合金含量及均匀化退火对热挤压组织的影响规律.本实验通过在Gleeble-1500D热模拟实验机上对不同Al含量的AZ10,AZ31,AZ61和AZ91镁合金进行热模拟挤压,结果表明,经过400℃/12h均匀化退火,AZ10和AZ31合金均形成单一的α固溶体,AZ61合金...     

凝固科学技术与材料

从凝固科学与实践发展的角度介绍了当前凝固材料体系的基本框架和凝固科学主要发展阶段的基本理论。作为材料科学与工程的基本组成，凝固科学技术正在现代科学理论的基础上针对传统材料的改性提高和新材料的发展需求，以控形、控构、控性为目标开展优质铸件的定向、晶体生长、快凝、深过冷及各种新型和超常领域凝固过程的研究，并介绍了其中某些方面和展望了可能的发展趋势。     

Development and challenges of planning and scheduling for petroleum and petrochemical production

Production planning and scheduling are becoming the core of production management, which support the decision of a petrochemical company. The optimization of production planning and scheduling is attempted by every refinery because it gains additional profit and stabilizes the daily production. The optimization problem considered in industry and academic research is of different levels of realism and complexity, thus increasing the gap. Operation research with mathematical programming is a conventional approach used to address the planning and scheduling problem. Additionally, modeling the processes, objectives, and constraints and developing the optimization algorithms are significant for industry and research. This paper introduces the perspective of production planning and scheduling from the development viewpoint.     

江澳两地高校文创设计的协同研究与商业实践

目的 探索江门世遗文化的传承、发展和转化的新思路,践行国家在《粤港澳大湾区发展规划》纲要中要求江门承担与港澳地区文化创意合作与开发任务的分工。方法 与澳门高校紧密合作,开展专业培训课程,以开平碉楼为例,从人文视角开展设计研究,梳理开平碉楼的文化脉络,把世遗文化的元素和其背后的文化融入文创产品中,提升文创产品的附加值,推动当地文创产业结构的变革。结果 两地高校构建了稳定的科研团队,开设长期有效的设计培训课程,与景区建立了研究协作关系,帮助景区构建了一套产销研的商业模式。结论 以跨区域高校合作为平台,以文创产品为抓手,依托江澳两地的资源优势,可以构建江门世遗文化全新的品牌形象,最终推动开平世遗文化的活化。     

Error and uncertainty in modeling and simulation

This article develops a general framework for identifying error and uncertainty in computational simulations that deal with the numerical solution of a set of partial differential equations (PDEs). A comprehensive, new view of the general phases of modeling and simulation is proposed, consisting of the following phases: conceptual modeling of the physical system, mathematical modeling of the conceptual model, discretization and algorithm selection for the mathematical model, computer programming of the discrete model, numerical solution of the computer program model, and representation of the numerical solution. Our view incorporates the modeling and simulation phases that are recognized in the systems engineering and operations research communities, but it adds phases that are specific to the numerical solution of PDEs. In each of these phases, general sources of uncertainty, both aleatory and epistemic, and error are identified. Our general framework is applicable to any numerical discretization procedure for solving ODEs or PDEs. To demonstrate this framework, we describe a system-level example: the flight of an unguided, rocket-boosted, aircraft-launched missile. This example is discussed in detail at each of the six phases of modeling and simulation. Two alternative models of the flight dynamics are considered, along with aleatory uncertainty of the initial mass of the missile and epistemic uncertainty in the thrust of the rocket motor. We also investigate the interaction of modeling uncertainties and numerical integration error in the solution of the ordinary differential equations for the flight dynamics.     

Density and viscosity of tetralin and trans-decalin

New measurements are reported for the density and viscosity of tetralin and trans-decalin. The density was determined from room temperature to 60°C for tetralin and to 95°C for trans-decalin. The kinematic viscosity was measured up to temperatures slightly above 100°C. Our results improve upon the values recommended by the American Petroleum Institute for these liquids.     

Creation and motion of dislocations and fracture in metal and silicon crystals

By making a step on one surface ( ) of a rectangular small paralellepiped copper crystal, dislocations could be created by the molecular dynamic method. The dislocation created was not a complete edge dislocation but a pair of Heidenreich-Shockley partial dislocations. Each time a dislocation was created, the stress on the surface was released. Small copper crystals having a notch were pulled (until fracture), compressed and buckled by use of the molecular dynamic method. An embedded atom potential was used to represent the interaction between atoms. Dislocations were created near the tip of the notch. A very sharp yield stress was observed. The results of high speed deformations of pure silicon small crystals using the molecular dynamics are presented. The results suggest that plastic deformation may be possible for the silicon with a high speed deformation even at room temperature. Another small size single crystal, the same size and the same surfaces, was compressed using molecular dynamic method. The surfaces are {110}, {112} and {111}. The compressed direction was [111]. It was found that silicon crystals are possible to be compressed with a high speed deformation. This may suggest that silicon may be plastically deformed with high speed deformation.     

SMC／BMC的回收与再利用

SMC／BMC废弃物对工业及环境造成了很大影响，指出了SMC／BMC回收再利用的紧迫性。通过对目前国际上SMC／BMC回收再利用的3种典型途径优缺点的对比，参照国外SMC／BMC回收再利用的先进方法，对我国SMC／BMC回收再利用提供了可行的建议．     

The Candela and Photometric and Radiometric Measurements

The national measurement system for photometric and radiometric quantities is presently based upon techniques that make these quantities traceable to a high-accuracy cryogenic radiometer. The redefinition of the candela in 1979 provided the opportunity for national measurement laboratories to base their photometric measurements on optical detector technology rather than on the emission from high-temperature blackbody optical sources. The ensuing technical developments of the past 20 years, including the significant improvements in cryogenic radiometer performance, have provided the opportunity to place the fundamental maintenance of photometric quantities upon absolute detector based technology as was allowed by the 1979 redefinition. Additionally, the development of improved photodetectors has had a significant impact on the methodology in most of the radiometric measurement areas. This paper will review the status of the NIST implementation of the technical changes mandated by the 1979 redefinition of the candela and its effect upon the maintenance and dissemination of optical radiation measurements.