简介：黄金矿业服务有限公司（GFMS）7日发布《黄金年鉴2010》预测，随着投资需求增长，黄金价格在今年下半年有望突破1300美元／盎司大关。GFMS董事长PhilipKlapwijk（菲利普·克拉普威克）指出，由于国际货币基金组织的售金计划促使总体官方售金量增加，以及金矿产量的进一步增长抵消了全球黄金废料供应的些许下降，

简介：TheDCcharacteristicsofSiGeHBTirradiatedatdifferentelectrondosehavebeenstudiedinacomparisonwiththoseofSiBJT.Generally,IbandIb-Ib0increase,Ic,Ic-Ic0andits+/-transitionVbeaswellasDCcurrentgainβdecreaseswithincreasingdose;increaseofIb-Ib0withincreasingdoseforSiBJTismuchlargerthanthatforSiGeHBT;βincreaseswithVbeorIb,butdecreasesatIb＜0.25mAwithIb,andcongregatesathigherdose;andadamagefactord(β)ismuchlessatthesamedoseforSiGeHBTthanforSiBJT.SiGeHBThasmuchbetteranti-radiationperformancethanSiBJT.SomeanomalousphenomenaforincreaseofIc,Ic-Ic0,Ib-Ib0andβatlowdosehavebeenfound.Someelectrontrapshavebeenmeasured.Themechanismofchangesofcharacteristicsisdiscussed.

简介：Thecharacteristicsoftemperatures,stressesandstrainsfieldshavebeenstudiednumericallyforatitaniumalloysheetweldedwithanimprovedgastungstenarcweldingmethod,inwhichatrailingspotheatsinkisintroducedtocontroltheweldingstressanddistortion.Theimpingingjetmodelisemployedtodescribetheintenseheattransferbetweenthecoolingmediaandthetopsurfaceoftheworkpiece.Theinfluenceofthedistancebetweenarcandheatsinkisinvestigated.Resultsshowthatthereisanidealrangeofdistance.Usingtheidealdistance,alowstressandnodistortionweldingstructurecanbederived.

简介：TheAl-alloyarc-weldingshapingsystembasedonarc-weldingrobotisestablished,andtheAl-alloyshapingmanufactureisrealizedwiththeDC(directcurrent)gasmetalarcwelding(GMAW).TheresearchindicatesthatthemetaltransfertypeofDCGMAW,heatinputandtheinitialtemperatureoftheworkpiecegreatlyaffecttheAl-alloyshapingbasedonarcweldingrobot.Onthepenetration,theweldwidthandthereinforcement,theinfluenceofweldingparametersisanalyzedbygeneralizedregressionneuralnetwork(GRNN)fitting.

简介：采用SEM、TEM、EDS、DSC、XRD和拉伸实验研究铸态7X50合金及其均匀化处理过程的组织演变。结果表明,铸态7X50合金相组成主要有S(Al2CuMg)、T(Al2Mg3Zn3)、MgZn2和少量的Al7Cu2Fe和Al3Zr相。均匀化处理过程中枝晶网和残留相逐渐减少,经(470°C,24h)+(482°C,12h)均匀化处理时,T相消失,S相有微量残留,Al7Cu2Fe相几乎没有变化。铸态合金的DSC曲线中在477.8°C处有一较强吸热峰,经470°C、1h均匀化后合金的DSC曲线在487.5°C处出现一个新的吸热峰,而经482°C、24h均匀化处理后合金在487.5°C处的吸热峰基本消失。在XRD谱中未出现T(Al2Mg3Zn3)相,这和T相与S(Al2CuMg)及MgZn2相相关的结论相吻合。预均匀化处理制备的板材中再结晶晶粒分数明显降低,抗拉强度和断裂韧性相对常规均匀化处理制备的板材分别提高约15MPa和3.3MPa·m1/2。