PAGEVIAZ91粉末状镁合金的氢化处理及组织演变摘要镁合金是目前最轻的金属结构材料具有比强度高、比刚度高、耐腐蚀、切削加工性能好、易于回收利用等一系列的优点，因而有着极其重要的应用价值与广阔的应用前景。但是，现有镁合金常温下的塑性变形能力和塑性加工性能仍然较低，限制了其应用。因此，提高各类镁合金的强度，改善其塑性，是拓展镁合金应用领域推动镁合金发展的关键。通过细化晶粒制备纳米晶镁合金，能够提高现有各类镁合金材料的强度和塑性，是发展镁合金的有效途径。当镁合金粉末经氢化—歧化—脱氢—重组工艺处理后，粉末的微观组织被大幅度细化到纳米级。进一步研究发现，当粉末经脱氢重组后，其晶粒虽有所长大，但仍可保持在纳米级，这一过程被称为HDDR处理。本文主要研究粉末状镁合金的氢化过程及温度、氢压对氢化过程的影响。本研究选择应用广泛的AZ91镁合金。采用“镁合金氩气中磨制成粉末→氢化处理→真空脱氢→组织性能分析测试”的工艺路线，来研究粉末状镁合金的氢化脱氢过程，对其微观结构，相组成的变化进行研究。利用X射线衍射(XRD)和扫描电子显微镜（SEM）对镁中MgH2的体积分数和表面形貌的变化进行分析。由于实验仪器出了故障，本次试验需先将仪器修理完善。关键词：AZ91镁合金，HDDR处理，氢化反应，晶粒细化，纳米晶材料HYDROGENPROCESSINGANDMICROSTRUCTUREEVOLUTIONOFAZ91MAGNESIUMALLOYABSTRACTMagnesiumalloysisthelightestmetallicstructuralmaterial.Duetotheuniqueproperties,suchashighspecificstrengthandrigidity,easytorecycleandsoon,theyhavegreatpotentialforstructuralapplications.However,becauseoftheplasticdeformabilityofmagnesiumalloysisquitepooratroom-temperature,whichisanintrinsicdrawbacktolimittheirapplications.So,enhancingthestrengthanddeformabilityofmagnesiumalloyisthekeytoexpandtheirapplicationsandpromotethedevelopmentofmagnesiumalloyindustry.GrainrefinementistheeffectualwaytoenhancingthestrengthanddeformabilityofMgalloy.Whenthemagnesiumalloymaterialwastreatedbyhydrogenation-disproportionation-dehydrogenation-restructuringprocess,themicrostructureofthematerialhasbeensubstantiallyrefinedtothenanoscale.Furtherstudiesshowsthatthematerialhasbeentreatedbydehydrogenationandrestructuringprocess,itsgrainswouldgrowup,butstillremainedatthenanoscale,whichiscalledHDDRprocessing.Thepapermainlystudieshowthesurfaceofblockmagnesiumalloyishydrogenatedandhowthetemperatureandhydrogenpressureeffecttothehydrogenation.Inthisstudy,AZ91hasbeenused,whichiscurrentlythemostpopularmagnesiumalloy.Westudythehydrogenationanddehydrogenationprocessoftheblockmagnesiumalloys,itsmicrostructure,phasecompositionandsurfacemorphologyby“magnesiumalloyingotslicespolishing–hydrogenated–vacuumdehydrogenation–organizationsperforman