宏观材料学的结构——技术科学分支的思考

本文讨论宏观材料学的结构 ,并思考技术科学的分支。全文分三段共十八个论点。“释题和思考”中 ,讨论材料学、宏观材料学、学科分支及结构四个命题 ;“宏观材料学的结构”中 ,提出了表征系统中组元和关系的结构图 ,论述了十个组元——逻辑、系统、简易材料论、材料史、材料经济、材料法律、材料选用、材料人才、材料科研、材料展望 ;最后提出四点启示——专科实用人才的人文素质 ,仕而优则学 ,交叉结合的新岗位 ,终生学习。

先进材料设计的若干前瞻性思考——兼评阻碍新材料商品化进程的种种因素

在资源和环境恶化的情况下,材料科学家和化学家从可持续发展的角度提出生态环境材料和绿色化学化工及环境友好材料的概念。材料是人类社会发展和技术进步及现代文明的物质基础和先导。为此现代先进材料设计应从根本上预测其环境的协调性。简要介绍现代先进材料设计的若干前瞻性思考及绿色化学-化工概念。从宏观和微观材料学角度讨论发展先进材料与可持续发展的关系,并兼评当前阻碍新材料商业化进程的种种因素。

图书推介

科学之科学与反观性，科学的文化意蕴——科学文化讲座，宏观材料学导论，从毕达哥拉斯到怀尔斯，从迪利克雷到维斯卡尔迪。

Effect of heating-rate on failure temperature of pre-loaded magnesium alloy

The response and failure of magnesium alloy AZ31 specimens subjected to different pre-loaded-stress levels and heating rates were investigated with a Gleeble-1500 thermo-mechanical material testing system.It is found that the increases of either pre-loaded stresses or heating-rates decrease the failure temperatures of the specimens.The metallographs of the tested specimens were also observed.It is shown that the high heating-rate may cause stronger local thermal inconsistency,which remarkably increases the microdefects and reduces the macroscopic mechanical properties of the material.

A Possible Macroscopic-Photo-Catalysis Mechanism in Solar Furnace

Based on the experimental results of Chen et al. to use the solar furnace and medium frequency induction furnace to extract boron impurity from metallurgical silicon, we propose a strong radiation catalysis mechanism to explain the difference of reaction rates in these two furnaces. The postulate assuming the photons striking on the material not only increase the thermal energy of the molecules of reactants but also lower down the energy barrier of the reaction to speed up the chemical reaction. It is believed the photon catalysis mechanism is unlversall in most of high temperature chemical reactions and looking forward to more evidences for the postulate proposed in this article.

Complex fields in heterogeneous materials under shock:modeling, simulation and analysis

In this mini-review we summarize the progress of modeling, simulation and analysis of shock responses of heterogeneous materials in our group in recent years. The basic methodology is as below. We first decompose the problem into different scales. Construct/Choose a model according to the scale and main mechanisms working at that scale. Perform numerical simulations using the relatively mature schemes. The physical information is transferred between neighboring scales in such a way: The statistical information of results in smaller scale contributes to establishing the constitutive equation in larger one. Except for the microscopic Molecular Dynamics(MD) model, both the mesoscopic and macroscopic models can be further classified into two categories,solidic and fluidic models, respectively. The basic ideas and key techniques of the MD, material point method and discrete Boltzmann method are briefly reviewed. Among various schemes used in analyzing the complex fields and structures, the morphological analysis and the home-built software, GISO, are briefly introduced. New observations are summarized for scales from the larger to the smaller.

Focuses of material science development in recent years

Materials science is an interdisciplinary field applying the properties of matter to various areas of science and engineering. This scientific field investigates the relationship between the structure of materials at atomic or molecular scales and their macroscopic properties. It incorporates elements of applied physics and chemistry. With significant media attention focused on nanoscience and nanotechnology in recent years, materials science has been propelled to the forefront at many universities. Materials science encompasses various classes of materials, including electronic materials, functional ceramics, magnesium, material and processes for flat-panel displays, eco/environmental materials, sustainable energy materials, transportation materials, electronic packaging materials, etc.

Effect of grain boundary on the mechanical behaviors of irradiated metals: a review

The design of high irradiation-resistant materials is very important for the development of next-generation nuclear reactors. Grain boundaries acting as effective defect sinks are thought to be able to moderate the deterioration of mechanical behaviors of irradiated materials, and have drawn increasing attention in recent years. The study of the effect of grain boundaries on the mechanical behaviors of irradiated materials is a multi-scale problem. At the atomic level, grain boundaries can effectively affect the production and formation of irradiation-induced point defects in grain interiors, which leads to the change of density, size distribution and evolution of defect clusters at grain level. The change of microstructure would influence the macroscopic mechanical properties of the irradiated polycrystal. Here we give a brief review about the effect of grain boundaries on the mechanical behaviors of irradiated metals from three scales: microscopic scale, mesoscopic scale and macroscopic scale.