简介:Thecreepmechanismofas-castMg-6Al-6Ndalloywasstudied.Thestressexponentforcreepis5.8undertheappliedstressesof50-70MPaat175°C.Theactivationenergyforcreepis189kJ·mol-1undertheappliedstressof70MPaintherangeof150-200°C.Thetruestressexponentandthresholdstressforcreeparecalculatedas4.96and10.2MPa,respectively.Thetruestressexponentindicatesthatitscreepmechanismbelongstothedislocationclimb-controlledcreep,whichisinagreementwiththemicrostructurechangesbeforeandaftercreep.ThehighvalueforstressexponentisattributedtotheinteractionofAl11Nd3phasewithdislocations.Theactivationenergyismorethantheself-diffusionactivationenergyofMg,whichisattributedtotheloadtransfertakingplacefromthematrixtoAl11Nd3phaseduringcreep.
简介:偏磷酸钙纤维(CMPF)以良好的生物相容性和降解特性在生物医用领域得到了较好的发展和应用,采用熔融纺丝法制备了作为医用复合材料增强相的偏磷酸钙纤维。开展了CMPF在不同pH值磷酸缓冲液中的降解试验,测试得到了纤维直径与降解时间的关系,提出了在任意pH溶液中CMPF直径达到设计指标的降解时间预测模型,最后用CMPF在蒸馏水中的降解试验初步验证了预测模型,并分析预测模型产生偏差的原因。
简介:在含有10%硫酸、5%硼酸和2%磷酸的混合电解液中,对2024-T3铝合金进行阳极氧化处理,以提高其耐腐蚀性能。使用电化学阻抗频谱分析研究阳极氧化处理后合金的腐蚀行为。利用塔菲尔图和盐水喷雾技术进行对比发现,与只用磷酸或硫酸和硼酸的电解液相比,使用含有10%硫酸、5%硼酸和2%磷酸的混合电解液阳极氧化处理后的2024-T3铝合金,具有更好的耐腐蚀性和持久性。该电解液可以替代普遍用于阳极氧化铝合金的铬酸盐浴。
简介:Theeffectsofprocessparametersonthemicrostructuralevolution,includinggrainsizeandvolumefractionoftheαphaseduringhotformingofaTC6alloywereinvestigatedusingcompressiontests.Experimentswereconductedonthematerialwith(α+β)phasesatdeformationtemperaturesof800,860,920,and950°C,strainratesof0.001,0.01,1,and50s-1,andheightdirectionreductionsof30%,40%,and50%.Afterreachingapeakvaluenear920°C,thegrainsizeandvolumefractiondecreasewithfurtherincreaseofdeformationtemperature.ThestrainrateaffectsthemorphologiesandgrainsizeofαphaseoftheTC6titaniumalloy.Atalowerstrainrate,theeffectofthestrainrateonthevolumefractionisgreaterthanthatatahigherstrainrateundertheexperimentalconditions.Theeffectsofthestrainrateonthemicrostructurealsoresultfromdeformationheating.Thegrainsizeoftheαphaseincreaseswithanincreaseinheightdirectionreductionafteranearlydrop.Theeffectofheightdirectionreductiononthevolumefractionissimilartothatofthegrainsize.AlloftheopticalmicrographsandquantitativemetallographyshowthatdeformationprocessparametersaffectthemicrostructureduringhotformingoftheTC6alloy,andacorrelationbetweenthetemperature,strain,andstrainrateappearstobeasignificantfuzzycharacteristic.