超细w(mo)基复合粉末的制备与其性能分析

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1、5.通过线扫描和点扫描的能谱分析研究了W与γ-(Ni,Fe)之间的固溶度与烧结温度的关系。结果表明，W在γ-(Ni,Fe)中的固溶度远大于γ-(Ni,Fe)在W相的固溶度。在固相烧结范围内，随着温度的升高，W在γ-(Ni,Fe)中的固溶度明显上升。当温度上升至1500℃烧结温度下，W从γ-(Ni,Fe)中析出，固溶度反而下降。6.所制备的W-Ni-Fe粉末具有良好的烧结性能。当烧结温度为1350℃时，其相对密度可达92%。当烧结温度为1450℃时，致密度达96%以上。烧结体中W晶粒约为3μm，其拉伸强度和抗弯强度最高可达650MPa和1359MPa。抗弯强度和拉

2、伸强度的上升曲线呈现出与致密化曲线不同的趋势，主要是经1500℃烧结所得烧结体因温度过高而导致W颗粒严重长大，力学性能显著下降，产生过烧行为。7.W-Ni-Fe烧结体的拉伸强度与烧结体的W晶粒尺寸和拉伸的断裂机制有关。固相烧结时，烧结体虽晶粒细小，但是颗粒之间粘结力小，拉伸断面呈现为脆性断裂，拉伸强度较低。但是随着烧结体温度的增加，致密度增大，断面中穿晶解理增多，当烧结温度为1450℃时，拉伸断面以W晶粒内穿晶解理断裂和粘结相的撕裂为主，呈现韧性断裂。但是当烧结温度为1500℃时，W晶粒急剧长大，呈延性断裂方式。关键词：Mo-Cu材料；W-Ni-Fe材料；超细粉

3、体；甘氨酸-硝酸盐法；烧结性能；显微结构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