材料科学基础07-相图-1.pptVIP

相图〔phasediagram〕物质有熔点：Al2O3,MgO，TiO2，SiO2Al2O3和TiO2混合在一起，多高温度下开始出现液相？Al2O3和TiO2混合在一起，在一定的温度下会发生化学反响吗？不同比例的Al2O3和TiO2混合在一起，反响后的产物组成有什么不同？开始出现液相的温度有什么不同？1

相图〔phasediagram〕2

相图〔phasediagram〕的作用Usedtodetermine反响方向〔reactionsdirections〕Reactions(automatically自动地)happenstowardtowhatdirection?Whatdrivesareactiontohappen?Reactionshappenstowardthedirectionwithwhichtheenergyofthesystems(materials)isminimized3

Whydoweneedtostudyphasediagrams?Manufacture〔制造〕ofmaterials(材料):PredictphasecompositionofrefractoriesCanyougiveanexample?Application/useofrefractories:understandslagcorrosion渣腐蚀bychemicalreactionCanyougiveanexample?ThisquestionmayberaisedwhenyouattendajobintervieworaninterviewforPhDcomprehensiveexamination4

PhasediagramsBEAWARE〔注意〕:Phasediagramsarephaseequilibrium〔平衡〕diagramsSolidreactionsinrefractoriesseldom〔很少〕reachcomplete〔完全的〕equilibriumAl2O3MgOMgAl2O41650?C5

DefinitionsofPhaseDiagramsBoundarybetweentheLiquidregionandtheCaOss+LiscalledtheLIQUIDUS.TheboundarybetweentheMgOssandMgOss+LiscalledtheSOLIDUSPointatwhichtheLIQUIDUSlinesmeetiscalledtheEUTECTICPOINT液相线:liquidus固相线:solidus最低共熔点:eutecticpoint6

DefinitionsofPhaseDiagramsMgOssrepresentsaMgO-richsolidsolutionwithCaOasthesoluteSimilarly,CaOssrepresentsaCaO-richsolidsolutionwithMgOasthesolute固溶体：solidsolution7

Whatdoweknowfromthediagram?LowesttemperatureatwhichliquidbeginstoformPrecipitationofMgOssfromCaOsswhentemperaturedecreasesMaximumamountofMgOinCaOssThecompositionoftheeutecticpointMeltingtemperatureComposition:组成Precipitation:析出8

DefinitionsofPhaseDiagramsLiquidphaseispresentatalltemperaturesandcompositionsabovethislineOnlysolidphaseMgOssexistsbelowthislineHomogeneousliquidsolutionMgOsolidsolutionCaOsolidsolutionSinglephaseregionsRegion：区域Homogeneous：均匀的9

DefinitionsofPhaseDiagramsCaOssa