已选分类
工学材料科学与工程
单选题铸锭凝固时如大部分结晶潜热可通过液相散失时，则固态显微组织主要为______。
单选题A type of harness test that compares a materials hardness to some 10 known minerals arranged in order of hardness. A) Scleroscope (HSc) test B) Mohstest C) Brinellhardnesstest D) Rockwell Hardness test
单选题Which ofthe following statement about hydrogen bonding is NOT correct? A) symmetrical charge distribution B) static electrical attraction between positive and negative charges C) an attraction force between adjacent charges with opposite signs D) the strongest ofthe secondary bonding
单选题熔体是______的混合物。
a．相同聚合度的聚合物和游离碱
b．不同聚合程度的各种聚合物
c．各种低聚物
d．各种高聚物
单选题______ are (is) used to speed sulfur vulcanizing. A) Accelerators and activators B) Carbon black C) Retarders D) Antioxidants
单选题三元系统相图中，若存在有n条界线，则此系统相图中能连接出______条连线。
a．3 b．n-1 c．n d．n+1
单选题Choose the correct statement about the wetting phenomenon. A．A fiber can be properly wetted by a matrix only when the surface energy of matrix is greater than that of the fiber B．A fiber can be properly wetted by a matrix only when the surface energy of matrix is lower that that of the fiber C．A fiber can be properly wetted by a matrix only when the surface energy of matrix is equal to that of the fiber D．It is nothing to do with surface energies of matrix and fiber
单选题点群为Fm3m的晶体结构属于______晶系。
A.等轴
B.六方
C.四方
D.正交
单选题下面关于位错应力场的表述中，正确的是______。
单选题fcc结构中分别在(111)和面上的两个肖克利位错(分别是1/6和1/6)相遇时发生位错反应，将生成______。
单选题Which statement ofelastic modulus is NOT correct? A) Elastic modulus is also known as Youngs modulus B) The higher the magnitude ofelastic modulus the stiffer the material C) Elastic modulus can be measured graphically in the elastic region ofthe stress-strain diagram D) The higher the magnitude of elastic modulus the weaker the interatomic bonding forces
单选题可热处理强化的铝合金，为提高其强度，常用的热处理方法是( )。 A．水韧处理 B．固溶处理 C．固溶处理+时效处理
单选题The major source ofraw materials for synthetic rubber. A) Hevea B) Oil C) Trees D) Corn
单选题在三元系相图中，三相区的等温截面都是一个连接的三角形，其顶点触及______。 (A) 单相区 (B) 两相区 (C) 三相区
单选题面心立方晶体的孪晶面(twinning plane)是______。
单选题在一定温度下具有一定平衡浓度的缺陷是______。
单选题在下列几类晶体中，形成间隙型固溶体的次序是______。
A.沸石＞CaFn＞TiO2＞MgO
B.MgO＞TiO2＞CaF2＞沸石
C.CaF2＞TiO2＞MgO＞沸石
D.TiO2＞MgO＞CaF2＞沸石
单选题在三元凝聚系统相图中，若存在有n条界线，则此相图中存在的连线数必是______。
单选题在面心立方晶体中原子层沿[111]堆垛时，______的堆垛成为孪晶。
单选题立方晶体中的[001]方向是______。 (A) 二次对称轴 (B) 四次对称轴 (C) 六次对称轴