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1、5.通過線掃描和點掃描的能譜分析研究了W與γ-(Ni,Fe)之間的固溶度與燒結(jié)溫度的關(guān)系。結(jié)果表明，W在γ-(Ni,Fe)中的固溶度遠大于γ-(Ni,Fe)在W相的固溶度。在固相燒結(jié)范圍內(nèi)，隨著溫度的升高，W在γ-(Ni,Fe)中的固溶度明顯上升。當(dāng)溫度上升至1500℃燒結(jié)溫度下，W從γ-(Ni,Fe)中析出，固溶度反而下降。6.所制備的W-Ni-Fe粉末具有良好的燒結(jié)性能。當(dāng)燒結(jié)溫度為1350℃時，其相對密度可達92%。當(dāng)燒結(jié)溫度為1450℃時，致密度達96%以上。燒結(jié)體中W晶粒約為3μm，其拉伸強度和抗彎強度最高可達650MPa和1359MPa。抗彎強度和拉
2、伸強度的上升曲線呈現(xiàn)出與致密化曲線不同的趨勢，主要是經(jīng)1500℃燒結(jié)所得燒結(jié)體因溫度過高而導(dǎo)致W顆粒嚴重長大，力學(xué)性能顯著下降，產(chǎn)生過燒行為。7.W-Ni-Fe燒結(jié)體的拉伸強度與燒結(jié)體的W晶粒尺寸和拉伸的斷裂機制有關(guān)。固相燒結(jié)時，燒結(jié)體雖晶粒細小，但是顆粒之間粘結(jié)力小，拉伸斷面呈現(xiàn)為脆性斷裂，拉伸強度較低。但是隨著燒結(jié)體溫度的增加，致密度增大，斷面中穿晶解理增多，當(dāng)燒結(jié)溫度為1450℃時，拉伸斷面以W晶粒內(nèi)穿晶解理斷裂和粘結(jié)相的撕裂為主，呈現(xiàn)韌性斷裂。但是當(dāng)燒結(jié)溫度為1500℃時，W晶粒急劇長大，呈延性斷裂方式。關(guān)鍵詞：Mo-Cu材料；W-Ni-Fe材料；超細粉
3、體；甘氨酸-硝酸鹽法；燒結(jié)性能；顯微結(jié)構(gòu)2PreparationandcharacterizationofsuperfineW(Mo)-basedcompositepowdersAbstractPowdermetallurgicalW(Mo)-basedalloysarewidelyusedinelectricalcontacts,aerospacedevicesandmanyothercomponentsduetotheirhighdensity,goodelectricalandthermalconductivity.Theyhaveattractedcon
4、siderableattentioninmilitaryandcivilian.ThedevelopmentofmodernscienceandtechnologyputsforwardhigherrequirementsonW(Mo)-basedalloys,andpreparationofnanocompositepowderandfine-grainalloyshaveattractedmuchattentions.Fine-grainW(Mo)-basealloyswithhomogeneousmicrostructurehaveexcellentcom
5、prehensiveproperties.Therefore,developmentofW(Mo)-basedalloyshasbecomeoneofthemaintopicsinW(Mo)-basedalloys.Nanosizedpowderscanimproveability,reducesinteringtemperatureandrefinemicrostructure.ItisdesirabletopreparesuperfineornanosizedW(Mo)basedalloys.Furthermore,thesinteringprocessal
6、sohassignificantinfluenceonthepropertiesofW(Mo)-basedalloys.BecauseoftheinitialpowdersandthesinteringprocessaretwointrinsicfactorsthataffectthemechanicalpropertiesofW(Mo)-basedalloys.Inthisdissertation,thetwofactorswereinvestigatedrespectively.Glycine-nitrateprocess(GNP)methodhasbeen
7、usedtoprepareoxideceramicpowdersandthepowdersshowgoodcompositionaluniformity,lowresidualcarbonlevelsandsmallparticlesizes.Inthiswork,thismethodwasemployedtoprepareprecursorpowdersofMo-Cuand95W-3.5Ni-1.5Fecompositepowders.Aftersubsequentcalcinationandreduction,superfinecompositepowder
8、swerefinally
