the pauli exclusion principle is the quantum mechanical principle which states that two or more identical fermions (particles with half-integer spin) can occupy the same quantum state within a quantum system simultaneously.
atoms are made from a nucleus of protons and neutrons and a cloud of electrons.
who set up the periodic table?
which kind of bond in h2o?
the following elements are alkali metals.
which kind of bonding will be mainly existed in ceramics?
electrons in atoms would follow these principles.
the following bonds can be treated as weak bonds or secondary bonds.
metal atoms become anions after they lost electrons.
when voltage is applied to an ionic material, entire ions must move to cause a current to flow, therefore, the electrical conductivity is very good.
what is the coordination number for fcc structure?
how many atoms in hcp?
the apf could not be same due to different crystal structure.
for a ceramic compound, what are the characteristics of the component ions that determine the crystal structure?
there are cations and anions in ceramics, therefore, the crystal could not be electrically neutral.
the chemical formula of a compound indicates the ratio of cations to anions, which must be stoichiometric.
what are molecular structure in polymer?
which bond can be existed in polymer?
the molecular weight of polymers is a fixed value.
a polymer chain is straight.
空位原子数的计算公式是哪个？
which of the following statement is incorrect.
点缺陷包含的类型
空位平衡浓度与哪些因素有关？
which of the following statements about solid solutions are correct.
所有晶体都包含缺陷。
晶体都呈现电中性。
which of the following statement about frankel's defect is incorrect.
下列属于热缺陷的有：
defects do occur alone.
杂质原子加入金属中将会导致形成固溶体或者第二相。
which of the following statement about the burgers vector is incorrect.
which of the following statements about dislocation are correct.
which of the following statement is correct.
螺型位错位错线垂直于伯格斯矢量。
刃型位错的位错线不一定是直线。
what is helpful in predicting phase transformation?
自由能主要由哪些因素决定？
every pure material is considered to be a phase.
sugar-water syrup solution and solid sugar are different phases.
possibly the easiest type of binary phase diagram to understand and interpret is that which is characterized by the________system.
the first step in the determination of phase compositions is to
for a binary system of known composition and temperature, that is at equilibrium, at least three kinds of information are available.
we can find _______single-phase regions in the copper-silver diagram.
in the bcc α ferrite, the maximum solubility is _____ wt% at 727℃.
from the previous example for the 60 wt%ni-40 wt% cu alloy at 1100℃, only the α phase is present.
we don’t have to employ the tie line if two phases are present.
of all binary alloy systems, the one that is possibly the most important is that for iron and carbon.
α iron has a bcc crystal structure.
in practice, not all steels and case irons have carbon contents less than 6.7 wt% c.
the maximum solubility of carbon in austenite, 2.14 wt%, occurs at___℃.
the form of iron-carbon phase can be ided into ( ).
the microstructure that develops in iron-carbon alloys depends on ( ).
δ-ferrite is stable only at relatively high temperatures.
the time necessary for the transformation to begin and then end depends on ( ).
the thickness ratio of the ferrite and cementite layers in pearlite is approximately ( ).
贝氏体的微观结构由______和______组成。
the first process to accompany a phase transformation is nucleation.
temperature plays an important role in the rate of the austenite-to-pearlite transformation.
in the iron-carbide phase diagram, when at the temperatures above the eutectoid and for all times, only austenite will exist.
martensite will appear on the iron-iron carbide phase diagram.
cementite is much harder but more brittle than ferrite.