掺Zn对YBa_2Cu_3O_(7-δ)超导体高场特性的影响

本文研究了掺Zn对YBa_2Cu_3O_(7-δ)烧结样品高场下超导电性的影响.根据磁测量结果,利用 Bean 模型计算临界电流密度 J_c 和磁通钉扎力 F_p 的结果表明:随着 Zn 含量的增加,J_c 随外场增大而下降的速率增大,F_p 也显著下降.而且,对于某些样品,F_p 随外磁场变化出现一个极大值.     

DISSOLUTION OF IRON TO COPPER IN Fe60Cu40 ALLOY BY MECHANICAL ALLOYING AND SUBSEQUENT DECOMPOSITION

A metastable alloy with composition Fe₆₀Cu₄₀ can be prepared in single phase of a fcc structure by mechanical alloying, although Fe-Cu system is virtually immiscible in its equilibrium state at ambient temperature. The M?ssbauer spectra of this supersaturated solid solution could be fitted by two subspectra whose hyperfine magnetic fields are 200 kOe and 250kOe. In this metastable alloy, the iron atoms at the interface are easy to form clusters characterized as α-Fe at a temperature below 250℃, whereas the iron atoms in the body will cluster together at a higher temperature above 350℃ and behave as γ-Fe, and then transform to ferromagnetic bcc iron occurs.     

我国的相图研究及展望

木文概述了新中国成立后，四十年来我国相图研究的发展和现状．近十多年来，我国的相图研究人员在国内、外发表了一系列报告和论文；形成了一支有一定实力的研究队伍；建立了全国性的学术组织；开展了国际学术交流；相图研究成果在我国日益受到关注．本文最后展望了我国相图研究的前景．     

高温合金

高温合金系指在高温下能够长期承受一定应力的金属材料。高温合金的发展与化学工业、动力机械制造业及现代的喷气技术、火箭技术、原子能动力技术的     

DISSOLUTION OF IRON TO COPPER IN Fe60Cu40 ALLOY BY MECHANICAL ALLOYING AND SUBSEQUENT DECOMPOSITION

A metastable alloy with composition Fe₆₀Cu₄₀ can be prepared in single phase of a fcc structure by mechanical alloying, although Fe-Cu system is virtually immiscible in its equilibrium state at ambient temperature. The M?ssbauer spectra of this supersaturated solid solution could be fitted by two subspectra whose hyperfine magnetic fields are 200 kOe and 250kOe. In this metastable alloy, the iron atoms at the interface are easy to form clusters characterized as α-Fe at a temperature below 250℃, whereas the iron atoms in the body will cluster together at a higher temperature above 350℃ and behave as γ-Fe, and then transform to ferromagnetic bcc iron occurs.     

18/8型不锈钢中σ-相的形成

本文叙述在含钼、钛的18/8型不锈钢中σ-相形成的过程及其对钢的性能的影响。金相及X线衍射分析证实:在复相铬镍不锈钢中,铁素体分解成σ-相以在850℃为最快。应用特殊的侵蚀剂及高倍的金相检查,发现σ-相的沉淀开始发生于铁素体相界;伴随着σ-相的形成,其周围铁素体重结晶为奥氏体。由于σ-相的形成,钢的硬度增加,韧性显著降低,因而严重地影响了钢的安全使用,但是适当的热处理可以恢复其原来的组织及性能。     

稀土金属间化合物的磁性能

本文概述了稀土金属间化合物的结构并讨论了结构与磁性能的关系。简要介绍了RKKY理论在稀土金属间化合物磁性能研究方面的应用。讨论了稀土—过渡金属间化合物中存在的交换作用的机理,在此基础上对(1∶5)和(2∶17)类型的稀土永磁材料的磁学性能进行了较深入的分析。同时列举了近年来研制的有代表性的稀土永磁材料的主要磁学参数,探讨了今后的发展趋势。