已选分类
工学材料科学与工程
单选题螺位错的位错线平行于滑移方向。
单选题The strength of a thermoplastic polymer such as polyethylene tends to increase after uniaxial deformation, because______. A．cross linking occurs during deformation B．oxidation occurs during deformation in air at room temperature C．polymer chains tend to align themselves with the chain axis oriented along the direction of deformation D．none of the above
单选题冷形变金属在回复阶段可消除______。
单选题菲克第一定律描述了稳态扩散的特征，即浓度不随______变化。 (A) 距离 (B) 时间 (C) 温度
单选题菲克第一定律(Fick's first law)描述了稳态扩散(steady-state diffusion)的特征，即浓度不随______变化。
单选题在MgO离子化合物中，最可能取代化合物中Mg2+的正离子(已知各正离子半径(nm)分别是：(Mg2+)0.066、(Ca2+)0.099、(Li+)0.066、(Fe2+)0.074)是______。
单选题______ involves transforming gases, liquids, and solid elements by chemical and physical means. where atoms and molecules are combined to form solid materials. A) Analysis B) Processing C) Synthesis D) Wroughting
单选题高分子的熔点随其晶片厚度的增加而______。
单选题影响淬火后残余奥氏体量的主要因素是( )。 A．钢材本身含碳量 B．奥氏体含碳量 C．加热时保温时间的长短 D．加热速度
单选题A field that involves the generation and application of knowledge relating to the composition, structure and processing of materials to their properties and use. A) Engineering Materials Technology B) Materials Engineering C) Materials Science D) Materials ScienceAnd Engineering
单选题不易产生交滑移的晶体结构为______。
单选题结构单元相同的高分子链，其结晶能力最高的异构体为______。
单选题Which is not the advantage of Carbon/Carbon composites? A) Stronger at high temperatures than at low temperature. B) Easy oxidation at high temperature C) High specific strength D) Good resistance to thermal shock.
单选题现有下列铸铁，请按用途选材。A．HT250B．KTH350-10C．QT600-2
单选题陶瓷一般是不导电的绝缘体，其原因是( )。 A．原子排列不规则 B．原子排列不致密，空隙多 C．原子结合键是离子键或共价键
单选题由Clausius-Clapeyron方程可知，随着压力的增加，γ-Fe转变成α-Fe的温度______。
单选题在非化学计量化合物ZrO2-x中存在的晶格缺陷是______。 a．阴离子空位b．阳离子空位c．阴离子填隙 d．阳离子填隙
单选题Alow molecular weight polymer additive that enhances flexibility and reduces stiffness and brittleness is referred as ______ A．Colorants B．Plasticizer C．Flame retardants D．Foam agents
单选题The results obtained from torsion test can be plotted as a ______ diagram. A) σ-ε B) s-N C) τ-γ D) T-θ
单选题What main advantage do cellular plastics offer? A．Reduced density B．Improved crystallinity C．Greater density D．Improved strength