变质温度对ZL114A合金组织和性能的影响

采用K2ZrF6作为变质剂对ZL114A合金进行变质处理,研究了变质温度对ZL114A合金的显微组织和拉伸性能的影响。结果表明,随着变质温度提高,变质效果先升高后降低,当变质温度为725℃时,变质效果最佳。此时,α-Al相大致呈等轴状,且晶粒尺寸较小,共晶Si多为细纤维状或短棒状,合金的屈服强度、抗拉强度和伸长率在铸态下分别为151MPa、176 MPa和4.3%,经T6热处理后分别提高到251 MPa、300 MPa和5.0%。     

K_2ZrF_6变质剂对ZL114A合金组织和拉伸性能的影响

使用K_2ZrF_6作为变质剂在722℃对ZL114A合金进行变质处理,研究了K_2ZrF_6加入量对铸态及T6热处理态下ZL114A合金的组织和拉伸性能的影响。结果表明:K_2ZrF_6变质剂加入量为1.00wt%~1.10 wt%时,ZL114A合金的变质效果最佳。在该条件下,组织中α-Al相大致呈等轴状,共晶硅相大多为纤维状或短棒状,α-Al和共晶硅间的界面圆化;铸态和T6热处理态下ZL114A合金均具有最好的综合拉伸性能。     

Sr变质剂对石膏型精铸ZL114A合金组织与性能的影响

通过ZL114A合金熔体添加和未添加Sr变质剂,研究了熔体处理条件对石膏型精铸热处理试样显微组织及力学性能的影响。结果表明,未变质铸态试样力学性能好于变质试样,而未变质热处理试样力学性能稍差,其主要原因在于Si相热变质不太充分。由于变质试样缩松缺陷很难消除,因此,对于ZL114A合金石膏型复杂薄壁件,采用未变质处理不失为一种选项。     

浇注工艺对金属型铸造ZL114合金力学性能的影响

ZL114合金具有很高的力学性能和很好的铸造性能,广泛的应用于航空航天以及民用工业领域.采用正交实验法,研究浇注温度、模具温度、变质处理温度和变质剂加入量等四个工艺参数对金属型铸造ZL114合金力学性能的影响.结果表明,影响其力学性能的主要工艺参数是浇注温度和变质处理温度,综合力学性能最佳的工艺参数是浇注温度为700℃,变质处理温度为720℃,变质剂加入量为1%和模具温度为250℃.     

浇注工艺参数对ZL114A合金热处理后性能的影响

ZL114A合金具有良好的铸造工艺性能,较好的力学、抗腐蚀和焊接性能,已广泛应用于我国航空航天以及民用等领域。利用拉伸机,对ZL114A合金拉伸试棒的性能进行测试,研究ZL114A合金的浇注温度和模具温度对合金抗拉强度和伸长率的影响。结果表明,浇注温度在700~710℃,模具温度在250~300℃时,合金的力学性能呈现最优。     

Ce及变质工艺对ZL101A合金组织的影响

研究了Ce加入量、保温时间、变质温度和冷却速度对ZL101A合金组织的影响.实验结果表明,在金属型铸造条件下,加入质量分数为0.8%左右的Ce时,ZL101A合金具有最佳的变质效果,共晶硅全部变为细小点状,而且保温6h仍有一定的变质效果;适当提高变质温度可以减少稀土Ce的用量,最佳变质温度为760℃;冷却速度对变质影响很大,当冷却速度为0.8℃/s时没有任何变质效果.     

金属型铸造条件下Sb元素对ZL114A合金共晶Si和拉伸性能的影响

ZL114A合金是我国自主研发的铸造亚共晶Al-Si合金,变质共晶Si是提高其室温综合拉伸性能的重要方法之一。利用室温拉伸试验、扫描电镜观察研究了Sb元素对金属型铸造条件下ZL114A合金铸态和热处理态组织以及性能的影响。结果表明,对于铸态的ZL114A合金,Sb的加入将共晶Si由板片状变质为纤维状或颗粒状;经过热处理的ZL114A合金,Sb的加入使共晶Si的长径比变小,球化程度更高。在金属型铸造条件下,Sb元素能够提高ZL114A合金铸态和热处理态的室温综合拉伸性能,热处理后添加Sb的合金的抗拉强度和伸长率远远高于我国航空标准所要求达到的值。综合考虑ZL114A合金铸态和热处理态的共晶Si相形貌以及室温拉伸性能,Sb元素的最佳含量(质量分数)为0.09%。     

ZL114A铝合金油路壳体低压铸造工艺研究

研究了低压铸造生产ZL114A铝合金油路壳体铸件中合金成分优化、晶粒细化变质以及熔体净化对ZL114A力学性能和微观组织的影响,并采用ProCAST软件对壳体铸造工艺和铸造过程进行了模拟优化。结果表明,成分优化、晶粒细化以及合金熔体纯净化处理可有效改善ZL114A合金的微观组织,使铸件局部力学性能超过技术指标要求;采用缝隙式浇注系统,配合厚大部位放置冷铁,可有效改善铸件内部质量,减少缩松缺陷。     

稀土元素钇对ZL205A合金铸态组织与性能的影响

向ZL205A合金熔体中加入不同含量的稀土元素钇,在同样条件下进行熔炼、浇注。利用光学显微镜、扫描电镜、能谱及热分析,研究钇对ZL205A合金铸态组织、性能及凝固过程的影响规律。结果表明,钇能使铝-铜合金的铸态组织得到细化并且对第二相θ-Al2Cu相具有变质作用;热分析表明不同含量钇均使得ZL205A合金的共晶温度下降,并缩小其凝固区间。加入少量稀土钇(0.05%)后,合金铸态性能有所提高,继续增加钇含量得到的合金铸态力学性能与原料ZL205A合金力学性能相同,钇含量达到0.3%时,合金晶粒细化效果最好,此时力学性能又有进一步改善。     

钇变质剂加入量对ZL114A合金组织和力学性能的影响

使用不同含量的钇对ZL114A合金进行了变质处理,并对使用金属型模具铸造的合金进行了T6处理,研究了钇变质剂加入量对ZL114A合金显微组织和力学性能的影响。结果表明,未变质时合金的硅相呈粗大的棒状,加入钇变质剂后,硅相的体积明显减小,圆整度提高,没有尖角存在,且T6热处理后绝大部分共晶硅由棒状变成颗粒状或球状,并且分布均匀。钇加入量为0.3%时铸态合金的力学性能最好,抗拉强度达到181 MPa,伸长率达到3.9%,与未变质合金相比,分别提高了15%、77%。经过综合考虑,钇的最佳加入量为0.3%。     

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.     

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.     

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.     

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...