简介:从90年代开始,我国利用外资的政策导向已开始从原来的注重吸收外资的数量逐步转向以提高外资的质量为核心,引导外资为我国的产业政策服务的轨道上来。从世界经济的格局来看,“80年代以来,国际投资关系出现了重大变化,发达国家已不再满足确保本国海外投资免受东道国的侵害,而是进一步谋求发展中国家清除对外国投资的限制,以彻底实现国际投资的自由化。”I进入gO年代以来,世界经济的全球化和自由化趋势得到了迅速发展,我国已经承诺于202O年实现贸易与投资自由化。在Trims等国际法制及发达国家要求放松对外资限制的压力和动力下,根据我国国民经济的发展现状及远景目标,在这一过程中,我国外资立法应采取相应的政策导向。总
简介:X-raydiffraction(XRD)anddifferentialscanningcalorimetry(DSC)wereusedtoinvestigatethecrystallizationprocessofamorphousAl90TMxCe10-x(atomfractionin%;TM=FeorNi;x=3,5)alloys.AgingeffectswereexaminedbyX-raydiffraction.ThestructurecorrespondingtotheprepeakfortheamorphousAl90Fe5Ce5alloyismorestablethantheamorphousmatrix,butitisnotstableforamorphousAl90Ni5Ce5alloyduringthefirstcrystallizationstageandevendecomposesatroomtemperature.AlthoughbothAl-NiandAl-Fehavestrongchemicalbonding,thecrystallizationonsettemperatureofamorphousAl-Fe-CealloysismuchhigherthanthatofamorphousAl-Ni-Cealloys,whichislikelycausedbythedifferentstabilityofthestructurecorrespondingtotheprepeak.ThecrystallizationonsettemperatureincreasesasCe/NiratioincreasesinamorphousAl90NixCe10-xalloys,whereasitdecreasesasCe/FeratioincreasesinamorphousAl90FexCe10-xalloys.AbetteratomicpackingproducesasCecontentincreasesbecauseofthesizemismatchinAlNi-CesystemsandasFecontentincreasesbecauseoftheincreasingFecentralstructuralunits.