Al-Sr中间合金制备及应用的发展现状

综述了近些年来Al-Sr中间合金的发展现状，包括制备工艺，应用现状及用Al-Sr中间合金变质处理Al-Sr合金存在的问题。介绍了Al-Sr中间合金组织形态对Al-Si合金变质效果的影响，以及改变中间合金组织形态的有关工艺；近年来锶与其他元素复合变质的研究进展；其他锶合金及锶在变质其他合金方面的应用。     

Al-Sr合金变质处理的研究和应用

简介了Al-Si合金变质处理的发展过程,用Al-Sr合金对ZL104合金进行了变质试验,指出了Al-Sr合金变质剂的变质工艺参数,认为Al-Sr合金变质剂有长效性、质量稳定、操作简便、不污染环境等优点,有推广前途。     

铝-锶合金长效变质剂的生产

涿州市轻金属加工厂及涿州市轻金属加工技术研究所同第一汽车制造厂工艺研究所及中国科学院长春应用化学研究所合作,开发研制了Al-Sr合金长效变质剂,两年来在一汽及一汽长春轻型发动机厂经过实验室和工业试用,证明效果全面良好.该厂于1991年4季度开始用Al-Sr合金变质剂取代三元盐变质剂,为在我国推广Sr变质开辟了新路.本产品已通过河北省省级产品与成果鉴定.现已投入批量生产.     

锶变质铝硅合金吸氢问题的研究及其精炼方法

Al-Si合金的加Sr变质工艺已从实验室进入实际生产应用,但增氢问题是Sr变质的主要缺点。本文探讨了Sr变质Al-Si合金增氢的原因,发现这些氢不是由于变质处理过程中Al-Sr中间合金与大气中水汽反应而产生的,而是Al-Sr中间合金本身含有大量的氢。质谱分析结果表明,Al-Sr中间合金中存有SrH化合物。各种精炼方法的比较试验表明,对Sr变质处理后的ZL102合金用多孔吹头通工业氩气精炼,除氢效果明显,对变质有效期影响较小,是一种较理想的精炼方法。     

应用Al—Sr合金变质处理的技术经济分析

Al-Sr合金是亚共晶和共晶Al-Si合金的理想变质剂,本文从变质有效期长、显著改善冶金环境、提高铸件力学性能和成品率,有重熔变质效果,降低铸件生产成本等方面,分析了应用Al-Sr 合金变质处理的技术和经济效益。     

近共晶Al-Si合金的晶粒细化

研究了Al-Sr变质剂和锆复合盐细化剂对高近共晶Al-Si合金宏观/微观组织的影响.结果表明:单一Al-Sr变质剂的加入,不仅改变了共晶硅的形貌,同时对合金的组织也有较明显的细化作用.这可能是由于锶的加入,改变了液态金属的结构,导致枝晶尖端前沿生长过冷度增加,降低了枝晶α(Al)固液界面能.当Al-Sr变质剂和锆复合盐细化剂共同作用时,随着熔体中锆含量的增加,铸锭的晶粒度显著减小,当熔体的锆含量超过0.35%,可获得细小、分布均匀的等轴晶,其宏观晶粒尺寸为100～120 μm.与Al-Zr中间合金相比,无论是细化效果还是抗衰退的能力都优于中间合金.     

变质剂Al-Sr中间合金的制备及其变质效果

用对掺法制备Al-Sr中间合金。试验表明，要获得锶的高实收率、锶的最佳加入温度应为780－850℃，不宜用含氯或氟的精炼剂精练，锶应以小块状加入。用自制的Al-Sr中间合金对ZL101铝合金进行变质处理，试验表明，Al-Sr中间合金能使Al-Sr合金中的硅相从粗大的针、片状转变成细小的纤维状，铝相电得到细化，变质效果长达5h。     

挤压铸造对Al-Sr中间合金性能及变质效果的影响

本研究采用金相显微镜、X射线衍射(XRD)、能谱分析及扫描电镜(SEM)等技术,对重力铸造制坯后热挤压成Al-Sr中间合金线材与挤压铸造制坯后热挤压成Al-Sr中间合金线材中Al4Sr相的微观形貌、晶粒尺寸和断口形貌进行了对比分析。试验结果表明,挤压铸造制坯后热挤压成形Al-Sr中间合金线材中的Al4Sr相呈细小颗粒状,分布均匀,等效圆半径约为25.4μm,合金伸长率达到24.74%。塑性的提高使得中间合金线材易于加工成卷。同时,挤压铸造制坯后热挤压成形的Al-Sr中间合金线材具有较短的变质孕育期,变质效果良好。     

Al-Sr变质剂对Al-18Mg_2Si合金微观组织和力学性能的影响

研究了不同质量分数Al-Sr变质剂对Al-18Mg2Si合金的微观组织和力学性能的影响。结果表明,随着Al-Sr变质剂质量分数的增加,Mg2Si相尺寸减小,同时出现从交联状Mg2Si相向正方形Mg2Si相的转变。但仅改变了相的形状、尺寸、分布,未改变其相组成,依然为Al和Mg2Si两相结构。经过Al-Sr变质剂处理后的Al-18Mg2Si合金的硬度、强度、伸长率均高于文献的性能指标。当变质剂质量分数为0.2%时抗拉强度最高;当变质剂质量分数为0.6%时,伸长率最高。     

汽车发动机缸套用铝硅合金的变质处理

采用Cu-P10和Al-Sr13对Al-25Si合金进行了变质处理,研究了两种单一变质剂对合金组织与物相的影响,并分析了组织转变特点。结果表明,在合金中加入4%Cu-P10和1.5%Al-Sr具有最佳的变质效果。     

Prospects of the Use of Synergetic Approach to Solution of Problems of the Science of Nanomaterials

A synergetic approach to solution of problems of self-controlled synthesis of nanostructures and creation of self-organizing nanotechnologies is considered in connection with the superproblem of creation of materials with functional properties resembling those of biosystems. __________ Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 7, pp. 55 – 61, July, 2005.     

Kinetics of the oxidation of metals — Influence of self-diffusion of metal

The importance of the self-diffusion of a metal during its oxidation by a gas is treated for the cases of nonstoichiometric oxides having either interstitial cation or cation vacancies. We have established a general relationship for the reaction rate when a mixed diffusion process occurs. From this relationship, we have shown that the pressure dependence can be different, according to whether the rate-determining process is the self-diffusion through the metal or through the product.     

胫骨生物陶瓷复合材料的微结构增韧机理

扫描电镜观察显示胫骨是一种由羟基磷灰石和胶原蛋白组成的自然生物陶瓷复合材料.羟基磷灰石具有层状的微结构并且平行于骨的表面排列.观察也显示这些羟基磷灰石层又是由许多羟基磷灰石片所组成,这些羟基磷灰石片具有长而薄的形状,也以平行的方式整齐排列.基于在胫骨中观察到的羟基磷灰石片的微结构特征,通过微结构模型分析及实验,研究了羟基磷灰石片平行排列微结构的最大拔出能.结果表明,羟基磷灰石片长而薄的形状以及平行排列方式增加了其最大拔出能,进而提高了骨的断裂韧性.     

Features of formation of the structure in production of blanks of disks of heat-resistant nickel alloys

Conclusions To provide a high level of mechanical properties in wrought blanks of cast ÉP741NP and ÉP962 alloys it is necessary to form controlled structures. A necklace-type structure formed in homogenizing isostatic treatment, subsequent thermomechanical working including alternation of the operations of deformation in the (+)-area and recrystallization anneals, and final heat treatment is preferable. The temperature conditions of all stages of thermomechanical working are strictly controlled, especially the final operation of deformation and heating for hardening. To eliminate hardening cracks and distortions it is necessary to use molten salts at t=600°C as quenchants. The use of multiple production operations makes it possible to significantly reduce the structural inhomogeneity related to inhertance of the original dendritic structure. However, the structure of the final semifinished product is nevertheless characterized by a difference in occurrence of the processes of polygonization and recrystallization between the former dendritic cells and the interdendritic spaces in deformation and heat treatment.To obtain structurally homogeneous blanks for gas turbine engine parts it is necessary to use basically new methods of remelting such as vacuum double electrode remelting and electron beam remelting with an intermediate vessel.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 12, pp. 25–29, December, 1991.     

Ab-initio calculation of enthalpies of formation of intermetallic compounds and enthalpies of mixing of solid solutions

A large number of ab-initio calculations of energies of formation of intermetallic compounds have been performed in the last 15 years. The currently used methods are listed. The paper presents a review of the aluminium based compounds which have been studied. Comparisons of calculated and experimental enthalpies of formation are provided for aluminim-3d and-4d transition metal alloys at equiatomic composition. The modelling of the enthalpies of mixing of solid solutions based on a given lattice is described.     

试论洋务派教师聘任的思想

洋务派在洋务学堂的办学活动中,为了解决西学专业学科的教学困难,采用了聘请外籍教师的应急措施.他们以真才实学,合同制管理作为主导思想,并认为这种解决师资的途径只是权宜之计,并非久远.从客观上看,洋务派的教师聘任思想有深刻的历史影响.     

Mechanism of Nucleation of Precipitates of Carbides of Refractory Metals Under Hot Rolling of Automotive Sheet Steel

Metal Science and Heat Treatment - The problem of formation of properties in microalloyed sheet steels is considered. The cause and the possible mechanism of precipitation of carbides of refractory...