Materials science: Difference between revisions

Materials scientists emphasize understanding how the history of a material (''processing'') influences its structure, and thus the [[Material properties|material's properties]] and performance. The understanding of processing -structure-properties relationships is called the materials paradigm. This [[paradigm]] is used to advance understanding in a variety of research areas, including [[nanotechnology]], [[biomaterial]]s, and [[metallurgy]].

Before the 1960s (and in some cases decades after), many eventual ''materials science'' departments were ''metallurgy'' or ''ceramics engineering'' departments, reflecting the 19th and early 20th-century emphasis on metals and ceramics. The growth of materialsmaterial science in the United States was catalyzed in part by the [[DARPA|Advanced Research Projects Agency]], which funded a series of university-hosted laboratories in the early 1960s, "to expand the national program of basic research and training in the materials sciences."<ref name=martin-pip>{{cite journal|last=Martin|first=Joseph D. |title=What's in a Name Change? Solid State Physics, Condensed Matter Physics, and Materials Science|journal=Physics in Perspective|date=2015|volume=17|issue=1|doi=10.1007/s00016-014-0151-7|pages=3–32|bibcode= 2015PhP....17....3M|s2cid=117809375 |url=http://dro.dur.ac.uk/29168/1/29168.pdf }}</ref> In comparison with mechanical engineering, the [[Nascent state|nascent]] material science field focused on addressing materials from the macro-level and on the approach that materials are designed on the basis of knowledge of behavior at the microscopic level.<ref name=":0">{{Cite book |last=Channell |first=David F. |title=A History of Technoscience: Erasing the Boundaries between Science and Technology |publisher=Routledge |year=2017 |isbn=978-1-351-97740-1 |location=Oxon |pages=225 |language=en}}</ref> Due to the expanded knowledge of the link between atomic and molecular processes as well as the overall properties of materials, the design of materials came to be based on specific desired properties.<ref name=":0" /> The materials science field has since broadened to include every class of materials, including ceramics, [[polymer]]s, semiconductors, [[magnetism|magnetic]] materials, biomaterials, and [[nanomaterial]]s, generally classified into three distinct groups: ceramics, metals, and polymers. The prominent change in materials science during the recent decades is active usage of computer simulations to find new materials, predict properties and understand phenomena.

A material is defined as a substance (most often a solid, but other condensed phases can be included) that is intended to be used for certain applications.<ref>[http://www.nature.com/nmat/authors/index.html "For Authors: Nature Materials"] {{webarchive|url=https://web.archive.org/web/20100801234616/http://www.nature.com/nmat/authors/index.html |date=2010-08-01 }}</ref> There are a myriad of materials around us; they can be found in anything from b<ref>Callister, Jr., Rethwisch. "Materials Science and Engineering – An Introduction" (8th ed.). John Wiley and Sons, 2009 pp.5–6</ref> Newnew and advanced materials that are being developed include [[nanomaterials]], [[biomaterial]]s,<ref>Callister, Jr., Rethwisch. Materials Science and Engineering – An Introduction (8th ed.)uildings and cars to spacecraft. The main classes of materials are [[metal]]s, [[semiconductor]]s, [[ceramic]]s and [[polymer]]s.. John Wiley and Sons, 2009 pp.10–12</ref> and [[Photovoltaic cell|energy materials]] to name a few.<ref>{{Cite journal |last1=Goodenough |first1=John B. |last2=Kim |first2=Youngsik |date=2009-08-28 |title=Challenges for Rechargeable Li Batteries |url=http://dx.doi.org/10.1021/cm901452z |journal=Chemistry of Materials |volume=22 |issue=3 |pages=587–603 |doi=10.1021/cm901452z |issn=0897-4756}}</ref>

Crystallography is the science that examines the arrangement of atoms in crystalline solids. Crystallography is a useful tool for materials scientists. One of the fundamental concepts regarding the crystal structure of a material includes the [[unit cell]], which is the smallest unit of a crystal lattice (space lattice) that repeats to make up the macroscopic crystal structure. Most common structural materials include [[Parallelepiped|parallelpiped]] and hexagonal lattice types.<ref>Callister, Jr., Rethwisch. "Materials Science and Engineering – An Introduction" (8th ed.) John Wiley and Sons, 2009</ref> New and advanced materials that are being developed include [[nanomaterials]]. In [[single crystal]]s, the effects of the crystalline arrangement of atoms is often easy to see macroscopically, because the natural shapes of crystals reflect the atomic structure. Further, physical properties are often controlled by crystalline defects. The understanding of crystal structures is an important prerequisite for understanding [[crystallographic defect]]s. Examples of crystal defects consist of dislocations including edges, screws, vacancies, self inter-stitials, and more that are linear, planar, and three dimensional types of defects. <ref>Callister, Jr., Rethwisch. "Materials Science and Engineering – An Introduction" (8th ed.). John Wiley and Sons, 2009</ref> New and advanced materials that are being developed include [[nanomaterials]], [[biomaterial]]s.<ref>Callister, Jr., Rethwisch. Materials Science and Engineering – An Introduction (8th ed.)</ref> Mostly, materials do not occur as a single crystal, but in polycrystalline form, as an aggregate of small crystals or grains with different orientations. Because of this, the [[Powder diffraction|powder diffraction method]], which uses diffraction patterns of polycrystalline samples with a large number of crystals, plays an important role in structural determination. Most materials have a crystalline structure, but some important materials do not exhibit regular crystal structure.<ref>{{Cite journal |last=Gavezzotti |first=Angelo |date=1994-10-01 |title=Are Crystal Structures Predictable? |url=http://dx.doi.org/10.1021/ar00046a004 |journal=Accounts of Chemical Research |volume=27 |issue=10 |pages=309–314 |doi=10.1021/ar00046a004 |issn=0001-4842}}</ref> [[Polymer]]s display varying degrees of crystallinity, and many are completely non-crystalline. [[Glass]], some ceramics, and many natural materials are [[Amorphous solid|amorphous]], not possessing any long-range order in their atomic arrangements. The study of polymers combines elements of chemical and statistical thermodynamics to give thermodynamic and mechanical descriptions of physical properties.

Materials, which atoms and molecules form constituents in the nanoscale (i.e., they form nanostructurenanostructures) are called nanomaterials. Nanomaterials are the subject of intense research in the materials science community due to the unique properties that they exhibit.

Nanostructure deals with objects and structures that are in the 1 – 100&nbsp;nm range.<ref>{{cite journal |url= http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=BJIOBN00000200000400MR17000001&idtype=cvips&gifs=Yes |author= Cristina Buzea |author2= Ivan Pacheco |author3= Kevin Robbie |name-list-style= amp |title= Nanomaterials and Nanoparticles: Sources and Toxicity |journal= Biointerphases |volume= 2 |date= 2007 |pages= MR17–MR71 |doi= 10.1116/1.2815690 |pmid= 20419892 |issue= 4 |url-status= live |archive-url= https://archive.today/20120703014917/http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=BJIOBN00000200000400MR17000001&idtype=cvips&gifs=Yes |archive-date= 2012-07-03 |arxiv= 0801.3280 |s2cid= 35457219 }}</ref> In many materials, atoms or molecules agglomerate together to form objects at the nanoscale. This causes many interesting electrical, magnetic, optical, and mechanical properties.

Microstructure is defined as the structure of a prepared surface or thin foil of material as revealed by a microscope above 25× magnification. It deals with objects from 100 &nbsp;nm to a few cm. The microstructure of a material (which can be broadly classified into metallic, polymeric, ceramic and composite) can strongly influence physical properties such as strength, toughness, ductility, hardness, corrosion resistance, high/low temperature behavior, wear resistance, and so on.<ref>{{Cite journal |last1=Filip |first1=R |last2=Kubiak |first2=K |last3=Ziaja |first3=W |last4=Sieniawski |first4=J |date=2003 |title=The effect of microstructure on the mechanical properties of two-phase titanium alloys |url=http://dx.doi.org/10.1016/s0924-0136(02)00248-0 |journal=Journal of Materials Processing Technology |volume=133 |issue=1–2 |pages=84–89 |doi=10.1016/s0924-0136(02)00248-0 |issn=0924-0136}}</ref> Most of the traditional materials (such as metals and ceramics) are microstructured.

Nanomaterials describe, in principle, materials of which a single unit is sized (in at least one dimension) between 1 and 1000 nanometers (10⁻⁹ meter), but is usually 1&nbsp;nm – 100&nbsp;nm. Nanomaterials research takes a materials science based approach to [[nanotechnology]], using advances in materials [[metrology]] and synthesis, which have been developed in support of [[microfabrication]] research. Materials with structure at the nanoscale often have unique optical, electronic, or mechanical properties. The field of nanomaterials is loosely organized, like the traditional field of chemistry, into organic (carbon-based) nanomaterials, such as fullerenes, and inorganic nanomaterials based on other elements, such as silicon. Examples of nanomaterials include [[fullerene]]s, [[carbon nanotube]]s, [[nanocrystal]]snanocrystals, etc.

[[File:Cfaser haarrp.jpg|thumb|right|upright=0.9|A 6&nbsp;μm diameter carbon filament (running from bottom left to top right) sitingsitting atop the much larger human hair]]

Other significant metallic alloys are those of [[Aluminium alloy|aluminium]], [[Titanium alloys|titanium]], [[copper]] and [[Magnesium alloy|magnesium]]. [[Copper alloys]] have been known for a long time (since the [[Bronze Age]]), while the alloys of the other three metals have been relatively recently developed. Due to the chemical reactivity of these metals, the electrolytic extraction processes required were only developed relatively recently. The alloys of aluminium, titanium and magnesium are also known and valued for their high strength to weight ratios and, in the case of magnesium, their ability to provide electromagnetic shielding.<ref>{{Cite journal |last1=Chen |first1=Xianhua |last2=Liu |first2=Lizi |last3=Liu |first3=Juan |last4=Pan |first4=Fusheng |date=2015 |title=Microstructure, electromagnetic shielding effectiveness and mechanical properties of Mg–Zn–Y–Zr alloys |url=http://dx.doi.org/10.1016/j.matdes.2014.09.034 |journal=Materials & Design (1980-2015) |volume=65 |pages=360–369 |doi=10.1016/j.matdes.2014.09.034 |issn=0261-3069}}</ref> These materials are ideal for situations where high strength to weight ratios are more important than bulk cost, such as in the aerospace industry and certain automotive engineering applications.