gd和gd系合金的磁热效应及组织分析

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1、型叁兰壁圭丝燕墨篁墼篮Gd和Gd系含金的磁热效应及组织分析耪辩学专盟蟒究生黄苍磐指导教凝踩嚣费教授室漱磁蒂Ⅱ冷技术困具育节能、环保等突出优点．越来越受到人们的关注。磁致冷毒孝鹣作为其中豹关键技术，它的发震其蠢举足轻重戆器擐。零文蓠先裁磁致冷浆蒸零缀莲、磁铡冷荚键疆零、疆致冷耪辜墨瓣发震等惩瑟敲了麓簧豹穰述。本文研究下列问题并取得进展。第一、采用赢接和间接测量法渤4试了不同纯度Gd存低场下(薹1．ST)的磁热效应；采用眈热法计算了磁热效应并同实际测量的磁热效应进行了比较，结果表明Gd的磁热效应随着杂质的增加而减小，届墨点簿蕊：第二、对

2、GdsSizGe2积Gd5$i19Ge2Sr毡{舍金进行了热楚理，实验络聚袋竣裹透熬楚理纛，会盒铸态豹磁蒸效疲褥翻了馥善，箕中1200℃／3h液氮冷龆热她理后。磁热效应比合金铸态提高3倍多，磁钝提高784％；第三、在Gd5sbGe2的研究基础上，聚用SEM和XRD释方法，观察Gd5sil9Ge2sm．t合金热她璎甜后微观组织结构的变化，结果表明夜热处理缓慢的冷龆条件．台金易于出城第二相：高温保激筹快速冷却，有利予影戒单相，从两改蒋了磁热戴应。关键词：Gd磁热效应热处理杂质微观组囊R结掏四川大学硕士学住论文Investigationo

3、nMagnetocaloricEffectandMicrostruetureofGdandGd—basedAlloysMajor：MaterialsScienceGraduateStudent：HuangCangbiTutor：Prof．ChenYungniMagneticrefrigerationtechnologyattheroomtemperaturehasattractedmoreandmorepeople’sattentionduetoitsadvantagesinvolvinginenergysaving，environ

4、mentalprotection．Tobekeyissue，magneticrefrigerationmaterialhasplayedanimportantroleinthetechnology．Firstlythearticlebrieflyintmducesthebasicprinciple，thekeytechnologyofmagneticrefrigerationandthedevelopmentofmagneticrefrigerants．Wehaveresearchedsomequestionsandmadesome

5、progressinthisresearch．Thearticleincludesthreeparts：i)directlyandindirectlymeasurethemagnetocaloriceffectofthedifferentpurityGdunderlowmagneticfield(≤1．5T)．andverifythemeasuredaccuracyofthemagnetocatoriceffectadoptingheatcapacity．Theresultindicatesthatthemagnetocaloric

6、effectisreducedwithincreaseoftheimpurity,Curietemperaturedecreased．ii)GdsSi2Ge2andGdsSit9Ge2Sn01alloyareheat-treated．Theresultindicatesmagnetocaloriceffectofthealloyingothavebeengreatlyimpmvcdbyheattreatmentathightemperature．especiallytheyhasmorethreetimesthantheformer

7、throughheattreatedbyliquidnitrogenholding1200℃for3h．iinThemicrostructureofas-castandheat-treatedGdjSb9Ge2Sn01alloyarewatchedbySEMandXRDinordertofindthecohesiverelationbetweenthemicrostructureandproperties．n玲resultindicatesthealloyeasilyf'ofmsthesecondphasebytheslowerco

8、olingduringheattreatment，andmakesmoleeasilyformingthesinglephasebyholdingtemperatureathightempemtureandquickercooling