Materials Science And Engineering MohammedOudah Al-Harbi Mechanical Engineering , College of Engineering, Majma’ah university, Saudi [email protected]/10/2017 Abstract: Thisreport discusses the structure, classification and the properties of thematerials also discusses the defects that distort the material and some testsfor the materials , through which the proper application of the material isdetermined .The aim of this study is to design new type of material basedon the properties and the structure ofthe materials. Key words: Materials , Smart materials , Tensile test . Indexes Table of Contents Abstract.
2 1.Introduction 3 2.Structure of materials 4 2.
1 Atomic structure. 5 2.2 Microstructure. 5 2.3 Macrostructure.
5 3.Classification of materials 6 4.Materials defects 7 5.Mechanical properties of materials 8 5.1 Tensile test 9 5.2 The process. 9 6.
Recommendation 10 7.Conclusion 10 References. 11 Table of FiguresFigure 1. 7Figure 2.
8Figure 3. 10 Table of TablesTable 1. 5 Table of Equations Equation 1. 9Equation 2. 10 1. IntroductionMaterialengineering is a subject that’s dedicated to explain the relation betweenmaterial science and its application, through Engineering point of view.
Materialscience, involve studying the correlation between material structure andmaterial property. ??1 The purpose ofstudying material engineering is to design and engineer a new type of materialbased on the known structure and property .The first educational institution that recognized the drive ofdiscovery and innovation in material engineering as a mean to serve socialneeds was the Department of material science and engineering (DMSE) at MIT (MassachusettsInstitute of Technology). The overlook of the of social needs consist ofconstruction , transportation , industrialization expansion. The development ofmaterials through (DMSE) was recognized in the second world war, The (DMSE) assistedin military manufacturing and development of new material.? ??5 2. Structure ofmaterialsAs it is knownall matters are made of atoms , there are about 100 kinds of atoms in theuniverse according to the periodic table .
The properties of materials dependson the atoms and atomic bond. Therefore, we can generally determine thedifferent behaviors of materials. The structureof materials is classified into three types based on size:1 – atomic structure2 –microstructure3 –macrostructure??6 2.1 Atomic structure The discovery of the inner structure of the atom is considered as aone of the most important scientific discoveries in this century. All atoms are made up ofthree subatomic particles : Protons , neutron and electrons.
These parts have the properties shown in Table1 :Table 1 Particle Charge Mass (g) Mass (amu) Proton +1 1.6727 x 10-24 g 1.007316 Neutron 0 1.6750 x 10-24 g 1.008701 Electron -1 9.110 x 10-28 g 0.000549 In Table1 the unit was used for atomic mass is (amu).
It is moreappropriate than gram for describing masses of atoms . ??6 2.2 Microstructure Microstructuredefined as the surface structure of materials such as thin foils which can bedetected after zooming 25 times at a microscopic level.The microstructure of the material can affect the mechanical andphysical properties such as strength , ductility , hardness and corrosionresistance. ??8 2.3 Macrostructure Macrostructure defined as The overall structure of the material andcan be seen by the naked eye. Materials behaves differently based on mass anddensity that behavior can be determined based on the atomic bonding , when weexamine a material in solid state at amicroscopic level we can notes visually the higher number of atoms incomparison with other material with low density in liquid state . based on thatobservation we can tell the differences in nature between solid and liquid.
Furthermore, at macro level liquid behaves differently than solid , for examplewhen you pour water out of a cup you can see the continuous flow of water. ??9 3. Classification of materialsMaterials has been used since the dawn of human existence fordifferent needs. humans life demands has been the driving force for discovering new typesof materials based on the demands such as using metals for heavy dutiesmachines.
furthermore, humans found ways to classify materials depending on theuse and needs of the materials The most common classification for materials is based on atomic bonding and atomic forces, thus, divided the materials into four categorize: 1 – Metals2 – Polymers3 – Ceramics4 – Composites ??7 In addition , some new materials have been developed by changingthe crystalline structure of the material. The change yield a new material withnew properties to suit a wantedapplication. we classify the new groupas smart material, the smart material is tailored from the four categories ofthe materials.
??2 Figure 1 Figure 1 shows the classification of material 4. Materialsdefects When discussing the defects of the materials we have to understandthe atomic structure of an atom. Crystalline material have atoms arrangementsover large atomic distance. The crystalline structure is defined as thearrangements of atoms. The lattice of the crystalline structure , is the 3darrangements of atoms. The defects of the material can occur over the atomicarrangement of the material, defects can be categorized based on impurity andvacancy.
??1 ??4 A defects can occur in into a hole between two lattice site whichis known as interstitial impurity. The second impurity when a particle vacant other particle bytaking its spot. Dislocation are hole that is not large enough for the particlevacancy. ??3 Figure 2 Figure 2 showing point defects, vacancy, interstitial impurity,substitutional impurities, and dislocations 5. Mechanicalproperties of materialsThe mechanical properties of materials are those which affects the strength and ability of materials.Some of mechanical properties Strength , Toughness , Hardness , Malleability , Brittleness ,Ductility , Creep There are some tests we have to do for the material to know themechanical properties for it and also we have to know the degree for themechanical property that we are testing the material for .
The mostimportant mechanical properties arestrength and ductility and we can test these properties by tensile test. ??3 5.1 Tensile testIs the test in which the sample is subjected to a controlledtension force until it reaches failure. Depending on the result, the test candetermine the extent of the material’s bearing to the forces effected on it inthe application that we test the material for.
??3 5.2 The processThe test is done by placing the sample on the testing machine andslowly extend by tensile force we apply on it until it reaches the failure .during the process we calculate the elongation and from it we can calculate thestrain by Equation 1 Equation 1 The force which we apply on the sample is used to find the stressby equation 2 Equation 2 ??3 specimen Figure 4 extensometer Figure 3 Figure 3 shows the typical tensile test machine 6. RecommendationTo choose the best material for an application we have to know theatomic structure and the defects thatcan occur in the material , also we have to do some tests on the material toknow its limitation such as tensile testing.For the use of smart materials , we must know their basicclassification and the changes which happened to them to know the original andnew properties of the material and this will help to know whether the materialsuitable for the application that we want or not .7. ConclusionMaterial is divided into different categorize based on their atomicbonding.
From that relation determinethe types of the materials based on the atomic structure. Mechanical testing can stress the materials to its limitation todefine the mechanical properties of the materials. By understanding themolecular structure of materials, thedefect at a microstructure level can be used to engineer a new type of material that compensate the flaws such as smartmaterial.Study of nanomaterials will be the future work . References Books:1 WilliamCallister-David Rethwisch , Fundamentalsof materials science and engineering an integrated approach , Wiley , 2016.
2 M.VGandhi-B.S Thompson , Smart materials and structures , Chapman and Hall ,1992 .3 R.Smallman , A.
Ngan, Physical metallurgy and advanced materials , ElsevierScience , 2011.4 JohnHook , Henry Hal , Solid state physics , John Wiley & Sons , 2010 . Websites:5 https://dmse.mit.
edu/about/history. 6 https://cbc-wb01x.chemistry.ohio-state.
edu/~woodward/ch121/ch2_atoms.htm .7 https://www.nde-ed.
org/EducationResources/CommunityCollege/Materials/Introduction/classifications.htm .8 https://www.corrosionpedia.
com/definition/777/microstructure .9 http://www.memidex.com/macrostructure.