金属不锈钢毕业论文外文文献翻译及原文

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1、毕业设计（论文）外文文献翻译文献、资料中文题目：金属、不锈钢文献、资料英文题目：文献、资料来源：文献、资料发表（出版）日期：院（部）：专业：班级：姓名：学号：指导教师:翻译日期:2017.02.14Unit1MetalsTheuseofmetalshasalwaysbeenakeyfactorinthedevelopmentofthesocialsystemsofman*Oftheroughly100basicelementsofwhichallmatteriscomposed，abouthalfareclassifiedasmetals.T

2、hedistinctionbetweenametalandanonmetalisnotalwaysclear-cut.Themostbasicdefinitioncentersaroundthetypeofbondingexistingbetweentheatomsoftheelement,andaroundthecharacteristicsofcertainoftheelectronsassociatedwiththeseatoms.Inamorepracticalway，however，ametalcanbedefinedasanele

3、mentwhichhasaparticularpackageofproperties.Metalsarecrystallinewheninthesolidstateand，withfewexceptions(e.g.mercury)，aresolidatambienttemperatures.Theyaregoodconductorsofheatandelectricityandareopaquetolight.Theyusuallyhaveacomparativelyhighdensity.Manymetalsareductile-that

4、is,theirshapecanbechangedpermanentlybytheapplicationofaforcewithoutbreaking.Theforcesrequiredtocausethisdeformationandthoserequiredtobreakorfractureametalarecomparativelyhigh，although,thefractureforcesisnotnearlyashighaswouldbeexpectedfromsimpleconsiderationoftheforcesrequi

5、redtotearaparttheatomsofthemetal.Oneofthemoresignificantofthesecharacteristicsfromourpointofviewisthatofcrystallinity.Acrystallinesolidisoneinwhichtheconstituentatomsarelocatedinaregularthree-dimensionalarrayasiftheywerelocatedatthecornersofthesquaresofathree-dimensionalche

6、ssboard.Thespacingoftheatomsinthearrayisofthesameorderasthesizeoftheatoms，theactualspacingbeingacharacteristicoftheparticularmetal.Thedirectionsoftheaxesofthearraydefinetheorientationofthecrystalinspace.Themetalscommonlyusedinengineeringpracticearecomposedofalargenumberofsu

7、chcrystals，calledgrains.Inthemostgeneralcase，thecrystalsofthevariousgrainsarerandomlyorientedinspace.Thegrainsareeverywhereinintimatecontactwithoneanotherandjoinedtogetheronanatomicscale.Theregionatwhichtheyjoinisknownasagrainboundary.Anabsolutelypuremetal(i.e.onecomposedof

8、onlyonetypeofatom)hasneverbeenproduced.Engineerswouldnotbeparticularlyinterestedin