一、①直到最近，科学家才终于了解材料的结构要素与其特性之间的关系。
It was not until relatively recent times that scientists came to understand the relationships between the structural elements of materials and their properties.
②材料工程学主要解决材料的制造问题和材料的应用问题。
Materials engineering mainly sloves the problems of manufacture and applications of materials
③材料的加工过程不但决定了材料的结构，同时决定了材料的特征和性能。
The processing of the materials not only decides their structure but also their properties and performance.
④材料的力学性能与其所受外力或负荷而导致的变形有关。
Mechanical properties of materials relate deformation to an applied load or force.
二、①金属元素有许多游离电子，金属材料的许多性质可直接归功于这些电子。
Metallic materials have large number of nonlocalized electrons , and many properties of metals are directly attributable to these electrons.
②许多聚合物材料是有机物，并具有大的分子结构。
Many polymer materials are organic compounds and they have large molecular structure.
③半导体材料的电性特征介于导电材料（如金属、金属合金）与绝缘体（陶瓷材料和聚合体材料）之
间。
Semiconductors have electrical properties that are intermediate between the electrical conductors (viz. metals and metal alloys ) and insulators (viz. ceramics and polymers).
④生物材料不能产生毒性，并且必须与人体组织互相兼容。
Biomaterials must not produce toxic substances and must be compatible with body tissue.
三、①从我们呼吸的空气到各种各样性质迥异的金属，成千上万种物质均是由100多种原子组成的。
These same 100 atoms form thousands of different substances ranging from the air we breathe to the metals which have different properties.
②事实证明金属原子是通过很强的键结合在一起的。
The facts proved that the atoms of metals are held together by strong bond.
③微观结构是指能够通过显微镜观察到的而不是用肉眼直接观察到的结构；宏观结构是指可以直接用
肉眼观察到的结构。
Microstructure, which includes features that cannot be seen with the naked eye but using a microscope. Macrostructure includes features that can be seen with the naked eye.
④原子核中质子和中字的量的总和就是原子量。
The atomic weight of an atom indicates how many protons and neutrons in the nucleus.
四、①化学性质是用来描述一种物质是怎样变成另外一种完全不同的物质的性质。
Properties that describe how a substance changes into a completely different substance are called chemical properties.
②相变是一种物理性质，并且物质存在四种相：固相、液相、气相和等离子体。
Phase is a physical property of matter and matter can exist in four phase: solid, liquid, gas and plasma.
③当温度低于熔点是，聚合物的晶体结构破坏，但其分子仍然连接在分子链上，从而形成一种柔软和柔顺性材料。
At some temperature below the melting point, they start to lose their crystalline structure but the molecules remain linked in chains, which results in a soft and pliable material.
④在工程应用中，渗透率通常用相对值而不是绝对值来表示。
In engineering applications, permeability is often expressed in relative, rather than in absolute, terms.
五、①通常，温度低于室温时，金属合金的强度性质增加，而延展性。
破碎韧度和拉伸性能降低。
Temperatures below room temperature generally cause an increase in strength properties of metallic alloys; while ductility, fracture toughness, and tensile properties usually decrease.
②从材料的角度来说，应力是一种在材料内部所分布的力，它可以平衡所施加的负荷并与其发生相互作用。
From the perspective of what is happening within a material, stress is the internal distribution of forces within a body that balance and react to the loads applied to it.
③工程应变可定义为：所施加力方向上的材料的改变量与材料原始长度的比值。
Engineering strain is defined as the amount of deformation in the direction of the applied force divided by the initial length of the material.
④高强度和高延展性的材料比低强度和高延展性的材料的韧性高。
A material with high strength and high ductility will have more toughness than a material with low strength and low ductility.
七、①金属有时被描述为由游离电子团包围的正离子晶格。
Metals are sometimes described as a lattice of positive ions surrounded by a cloud of delocalized electrons.
②通常地，金属具有良好的导电性和导热性，具有金属光泽，密度较大，并且具有在压力下变形而不
会断裂的能力。
Metals in general have superior electric and thermal conductivity, high luster and density, and the ability to be deformed under stress without cleaving.
③合金是指两种或两种以上的元素形成的固溶体混合物，其中主要组分为金属。
An alloy is a mixture of two or more elements in solid solution in which the major component is
a metal.
④不同比率的金属结合成为合金可以改变纯金属的性质，从而产生所需要的性能Combining different ratios of metals as alloys modifies the properties of pure metals to produce desirable characteristics.。