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1、第1章金属的晶体结构TheintroductionMetalologyisthestudyoftherelationshipbetweenthecomposition,organization,structureandmechanicalpropertiesofmetalsandalloys・Themechanicalpropertiesarethestrength,hardnessandplasticityofthemateria1.Thepartsrequiredtobeartheloadhavecertainmechanicalproperties
2、,whichwecallstructuralmaterials・Correspondingtoanotherkindofmaterialandstructuralmaterialisfunctionalmaterial,itusuallydoesnotrequiretheloadbearingandmainlytheuseofitsphysicalproperties,suchaslight,electricity,magnetic,etc・Functionalmaterialsuseittomakeallkindsofsensorsforthesens
3、itivepropertiesoflight,electricityandmagnetism・Metalsonlydiscussthemechanicalpropertiesofmetalmaterials,notphysicalproperties・Solidmetalisusuallyacrystal,andthesmalleststructuralunitofmetalstudiesisatoms・Atomscanformdifferentcrystalstructuresbydifferentarrangement,producingdiffer
4、entproperties・Theatomicstructureisnotastudyofmetals・ThecrystalstructureofthemetalITmetalandmetalbondsThedefinitionofmetalsvariesaccordingtothediscipline・Itendtobedividedbythenatureofthebond,whichisametalbond.Thebenefitofthisclassificationisthatithelpstoexplainthephenomenaassociat
5、edwithmetal-mechanicalperformance・Forexample,whydometalshavebetterplasticity?Whatisametalbond,anionicbond,acovalentbond,andwe'veknownforalongtimethatthebiggestfeatureofmetalbondsisunsaturatedanddirectionless・Andthenwe，11seethatit'sthesecharacteristicsthatmakethemetalmoreplastic・S
6、tudieshaveshownthatsolid-statemetalsareusuallycrystals,andtheirstructurestendtobedenselystacked・Whyisthat?Let'suseatwo-atommode1.Whentwoatomsareveryfarapart,theydonotinteract・Astheymovecloser,thenucleusofanatomwillcausegravitywiththenucleusofanotheratom・Andthenucleiandelectronsof
7、thetwoatomsarerepulsive・Theresearchshowsthatgravityisalongdistanceforce,andtherepulsionisashort-rangeforce,whichmeansthatthegravitationalforceisgreaterthantherepulsiveforcewhenitisfartheraway.Astheatomicdistancedecreases,therepulsiveforceincreasesfasterthangravityincreases・Obviou
8、slytheresultofthisactiontheremustbeabala
