失稳区A1-Li合金回归机制的计算机研究

基于离散格点形式的微扩散方程，对失稳区Al-Li合金在回归过程中Al3Li(δ’)相溶解做原子层面计算机模拟，分析析出相在回归过程中原子图像、序参数的演化，进而探讨Al-Li合金的回归机制。探明在失稳区Al-Li合金的回归过程有序相演化序列为：化学计量比δ’相→非化学计量比有序相→无序基体。失稳区合金的回归过程为“小范围的成分回落”，而时效过程为“大范围的成分起伏”，因此，在失稳区合金回归过程并非时效过程的逆过程。     

Cu,Li含量对新型超高强铝锂合金力学性能及微观组织的影响

利用力学性能测试和TEM分析测试手段,计算出铝锂合金Al-(3.6%~4.15%)Cu-(1.1%~1.4%)Li中非固溶Cu,Li原子摩尔分数总和及Cu/Li原子摩尔分数比,分析了强度和微观组织之间的影响机理.结果表明,合金中的主要时效强化相为大量T1相(Al2CuLi)和少量θ′相(Al2Cu),Li含量较高的合金可能析出的极少量δ′相(Al3Li).在上述成分范围内,随Cu含量或Li含量增加,合金强度提高,且Li含量的增加幅度不同,对合金强度的提高幅度存在明显的差异.非固溶Cu,Li原子摩尔分数总和及其比例共同作用,通过影响析出相总量、类型及各析出相分数决定合金强度.要获得铝锂合金的超高强度,在提高Cu,Li原子摩尔分数总和的同时,还要提高其比例.     

有序相临界晶核判据的计算机研究

利用微扩散方程对有序组成核过程进行计算机模拟，对经典理论的假设进行验证。新相胚牙不是经典成核理论假设的那样，在一开始就达到了化学计量比，而是在时效的过程吕，而是在时效的过程中，由非化学计量比逐渐向化学计量比演化。在演化过程中，有许多B位原子占位几率低而尺寸较大的胚芽因不稳定而消失，一些B位原子占位几率高的较小胚芽却稳定存在并继续长大。仅利用胚芽的尺寸作为临界晶核的判据并不充分，有序相临界晶核的判据应包括B位原子的占位几率。     

应力作用下1420Al-Li合金的腐蚀行为研究

通过动电位极化曲线、电化学阻抗谱,并结合SEM图,研究恒应力作用下1420Al-Li合金在3.5%NaCl溶液中的腐蚀行为.结果表明:随着应力增加,材料的腐蚀加剧;合金主要腐蚀类型为孔蚀,这是由于合金的主要时效强化相为δ'相(Al3Li),它作为阳极相均匀弥散分布在基体中,晶界处仅有少量的S(Al2MgLi)相.     

应力作用下1420Al—Li合金的腐蚀行为研究

通过动电位极化曲线、电化学阻抗谱，并结合SEM图，研究恒应力作用下1420Al-Li合金在3．5％NaCl溶液中的腐蚀行为．结果表明：随着应力增加，材料的腐蚀加剧；合金主要腐蚀类型为孔蚀，这是由于合金的主要时效强化相为δ’相（Al3Li），它作为阳极相均匀弥散分布在基体中，晶界处仅有少量的S（Al2MgLi）相．     

Al-Cu-Mg合金析出相的原子成键与性能

根据固体与分子经验电子理论（EET），计算Al-Cu-Mg合金时效初期形成的GPB区和S″相的价电子结构。结果表明，GPB区具有较强的共价键络，而S″具有较强的总共价成键能，这两种析出相的主体共价键络都对合金基体具有增强作用。同时从价电子结构层次和析出相中Al原子的总成键能力合理解释了GPB区演化为S和S相的相变机理，并说明了相变对合金的强化作用。     

时效析出对Al-Zn-Mg-Cu合金热稳定性的影响

采用透射电镜、常温力学性能测试等手段,研究了合金成分与回归再时效工艺对Al-Zn-Mg-Cu合金热暴露过程中力学性能和微观组织的影响。研究结果表明,GP区和η'相的粗化是导致铝合金热暴露过程中强度降低的主要原因。在120 ℃热暴露时,高度弥散分布的GP区有利于提高Al-Zn-Mg-Cu合金的热稳定性,而在150 ℃热暴露时,添加与空位有较高结合能的Zr和Ti元素可以降低溶质原子的扩散速度和析出相的粗化速度,抑制GP区向η'相的转变。     

Ni75AlxCr25-x合金时效组织演变行为微观相场模拟

利用三元微观相场动力学模型,结合原子图像、有序相颗粒半径和和体积分数等手段模拟研究不同浓度的Ni(75)Al(x)Cr(25-x)合金973K下的时效组织演变行为.结果表明,x=6,8,10三种Ni(75)Al(x)Cr(25-x)合金时效过程中均析出DO(22)和L1(2)两种有序相.随着Al含量的增加,L1(2)相颗粒的尺寸增大,体积分数增加,相应的DO(22)相颗粒的尺寸减小,体积分数减少.无论DO(22)相还是L1(2)相,在考虑弹性畸变能的影响后,有序相颗粒平均半径的立方与时间之间仅仅在粗化初期的某一阶段,近似的呈线性关系.整体I上来看,不满足LSW粗化理论.     

新型钴基高温合金长期时效组织演化研究

新型钴基高温合金具有比镍基高温合金更高的γ′强化相稳定温度,其有望替代镍基高温合金应用于涡轮盘等服役环境苛刻的工程部件。为了解决钴基高温合金长期服役环境下的组织稳定性,对两种不同C含量的新型钴基高温合金进行900℃长期时效研究,系统解析了铸造态和固溶时效2种处理条件下γ′相和碳化物的尺寸、分布、成分和形貌演化规律。研究结果表明：两种钴基高温合金中γ′相的粗化均遵循LSW熟化理论,固溶时效态合金中γ′相的粗化速率高于铸态合金;含C钴基高温合金中的碳化物形貌和尺寸在长期时效过程中未见明显变化,当时效时间达到5000 h后,碳化物周围出现无析出区,并且固溶时效态合金中碳化物周围的无析出区面积更大,这主要是Ta、Ti等元素扩散降低了γ′相的热稳定性并发生溶解造成的。     

温度对Al-11.4%Li合金沉淀机制影响的微观相场模拟

利用微观相场法模拟Al-11.4%Li合金时效过程中的微观组织.从模拟结果可以看出,该合金在383,423和493K下沉淀机制分别为失稳分解,非经典形核与失稳分解的混合机制和非经典形核长大.随温度的升高,新相颗粒逐渐规则,溶质原子的簇聚程度以及体系整体的有序化程度都在不断的降低.     

Current situation and future trend of China rare earth luminescent material industry

<正>Rare earth luminescent material is one of the most important application sectors of rare earths.China enjoys the exceptional advantage to develop rare earth luminescent material for its abundant rare earth resources.After several decades'endeavor,China's rare earth luminescent material industry,headed by rare earth phosphor for lamp and LED and high efficient rare earth energy-saving light source,has been gradually developed into a scale industry.China has become a major production base of rare earth phosphor for lamps and rare earth     

China rare earth market review

正June 1~10,2014Rare earth market remained weak.Quoted price of rare earth products was similar to that in May.There was no sign of recovery in downstream market.The market of NdFeB magnetic materials and phosphor was depressed.Catalyst,polishing powder and ceramic industries remained inactive.Demand from downstream industry was soft.Consumers purchased on their needs.Suppliers had strong intention to sell.Prices of rare earth products     

Annual Report analysis of Chinese rare earth-related listed companies in 2013

<正>Chinese rare earth-related listed companies have published their 2013 annual reports.It can be understood from their reports that production and operation activities of Chinese rare earth-related companies were still heavily affected by macro economy and industrial policies.They basically followed the steps of national economy.In 2013,world economy recovered slowly but the economy     

Market opportunities and challenges for rare earth polishing powder

正1.Status of rare earth polishing powder Rare earth polishing powder with high content of cerium oxide began to replace iron oxide for glass polishing and became one of the key materials in glass polishing process since 1940.Compared with traditional iron oxide,rare earth polishing powder has many advantages,such as fast polishing rate,high polishing quality and long service life.It can achieve good surface quality and improve operation conditions.For example,in lens polishing,the polishing work that cerium     

Baotou Research Institute of Rare Earths developed a new RE alloy preparation technology

正Pyrometallurgy Laboratory of Baotou Research Institute of Rare Earths had independently developed a new preparation technology of rare earth alloy for NdFeB.The alloy can remarkably enhance the coercivity of NdFeB magnet but also evidently reduce the production cost of the magnet.The new master alloy was prepared in the kA pilot-scale electrolytic cell by the independent technology.The rare earth master alloy can be used as the raw material for NdFeB.Compared     

Market and recycling of NiMH battery

<正>Market status and future trend of NiMH battery1.Global market of small NiMH battery Global market size of small NiMH batteries declined year on year since 2011.The trend will continue to 2018,at the rate of 5%to 10%annually.Demand for small NiMH batteries will be stable gradually.Many electrical apparatuses are powered by the built-in lithium battery today,which is the main reason for the shrunk market of small NiMH batteries.But,for some products,small NiMH     

China rare earth market review

正September 1-10,2014 Affected by the National Day holiday,rare earth transaction was stagnant and the market showed a weak steady state.As there was no good news for downstream market,some products with flat demand would likely rally slightly for some time to     

2014 second batch of rare earth quota released

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矿用防爆轴流对旋主要通风机叶片ANSYS模态分析及应用

高效节能矿用防爆对旋主要通风机的叶片是主要通风机运行的关键部件,叶片在运行时不断受到气流的作用力,从而使叶片产生振动,当叶片振动的频率与叶片的固有频率接近时,容易产生共振从而导致叶片的断裂。一旦叶片断裂时,对主要通风机的安全运行产生致命的影响,从而导致矿山、化工等企业发生重大事故,将会产生不可估量的损失。基于有限元分析软件ANSYS,对高效节能矿用防爆轴流对旋主要通风机叶片进行模态分析及产生对应的六阶模态频率,对主要通风机叶片的运行频率、固有频率及产生的共振问题进行了原理分析,并且解决了叶片频率共振的问题,从而为主要通风机叶片结构设计提供理论依据,并对主要通风机叶片的安全运行提供保障。     

2013 NdFeB export analysis

<正>China totally exported nearly 24,000 tonsof NdFeB products during 201 3,including 18,825 tons of permanent magnet,valued USD 1.34 billion at an average price of 71.4 USD/kg;3,277 tons of NdFeB magnetic powder,valued USD 1 01 million at an average price of 30.9 USD/kg;1,334 tons of strip casting ribbon,with total export value of USD 74million at an average price of 55.3 USD/kg;and 586