共查询到20条相似文献,搜索用时 750 毫秒
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针对镁合金室温强度低、塑性差的问题,采用复合挤压工艺在250℃对Mg-4Sn-2Al-1Zn合金进行了挤压,研究了复合挤压对合金的组织演变、织构及力学性能的影响。结果表明,复合挤压能将Mg-4Sn-2Al-1Zn合金的晶粒尺寸由45.2μm细化至3.1μm,组织均匀。挤压后的合金硬度提升,均匀性改善,屈服强度、抗拉强度和断后伸长率分别为204 MPa、287 MPa和21.0%,较匀质态分别提高了140.0%、91.3%和156.1%。动态再结晶是晶粒细化的主要机制,晶粒细化以及挤压后基面织构增强、织构向挤压方向均匀扩展使合金强度、塑性提高,挤压过程中Mg2Sn相破碎进一步提高了合金的力学性能。上述研究表明复合挤压是一种能有效提高镁合金综合性能的工艺。 相似文献
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对长宽比较大的扁形截面钛铜复合捧的挤压模具进行了设计研究。通过合理选材,并选择使挤压力最小的模具模腔轮廓曲线和半模角,改变模孔工作带的几何形状与尺寸,选择适当的挤压速度等,优化设计制备出扁形钛铜复合棒专用挤压模具。增加工作带长度可以增大摩擦阻力,使向该处流动的供应体的流动静压力增大,迫使金属向阻力小的方向流动,从而使型材整个断面上金属流量更加均匀。挤压实验结果表明,合理的模具设计对挤压材的挤压过程和挤压制品质量有重要影响,锥形模具更适合于扁形钛铜复合棒的挤压。解决了科研生产实际对大的长宽比扁型钛铜复合棒的需求。 相似文献
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Plasma nitrocarburising was carried out in a CO gas atmosphere with 3 mbar at 570°C for various times to investigate the effect of treatment time on the structure of the compound layer. The compound layers produced were composed of mainly the γ' phase for a slow cooled specimen and mixed γ'/ε phases for a fast cooled specimen during the initial stage. With the increasing of the treatment time up to 10 hours, the proportion of the ε phase relative to the γ' phase in the compound layer and the compound layer thickness were increased. When the treatment time was further increased to 30 hours, an anomalous phenomenon was observed: the ε phase was not stabilised and the compound layer thickness was decreased. It was found that the anomalous compound layer growth is associated with the removal of surface material by sputtering or the formation of oxynitride. 相似文献
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Jong Min Byun Su-Ryong Bang Chun Woong Park Myung-Jin Suk Young Do Kim 《Metals and Materials International》2016,22(1):81-86
In general, size, shape and dispersion of phases in alloys significantly affect mechanical properties. In this study, the mechanical properties of Mo-Si-B alloys were experimentally investigated with regards to the refinement of intermetallic compound. To confirm the size effect of the intermetallic compound phases on mechanical properties, two differently sized intermetallic compound powders consisting Mo5SiB2 and Mo3Si were fabricated by mechano-chemical process and high-energy ball milling. A modified powder metallurgy method was used with core-shell intermetallic powders where the intermetallic compound particles were the core and nano-sized Mo particles which formed by the hydrogen reduction of Mo oxide were the shells, leading to the microstructures with uniformly distributed intermetallic compound phases within a continuous α-Mo matrix phase. Vickers hardness and fracture toughness were measured to examine the mechanical properties of sintered bodies. Vickers hardness was 472 Hv for the fine intermetallic compound powder and 415 Hv for the coarse intermetallic compound powder. The fracture toughness was 12.4 MPa·√m for the fine IMC powders and 13.5 MPa·√m for the coarse intermetallic compound powder. 相似文献
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采用物理吸附方法将溶菌酶固定在MCM-41介孔分子筛上,并与化学缓蚀剂[氨基三亚甲基膦酸(ATMP)与聚天冬氨酸(PASP)]复配用作循环冷却水缓蚀剂。利用电化学法分析复配缓蚀剂的缓蚀机理,并用失重法所测得的复配缓蚀剂缓蚀性能为指标优化复配条件。结果表明:复配缓蚀剂为混合型缓蚀剂,可以同时抑制腐蚀过程的阴极反应与阳极反应,最佳复配方案为固定化溶菌酶投加量0.7g/L、ATMP质量浓度10mg/L、PASP质量浓度20mg/L,缓蚀率可达88.55%,循环冷却水对碳钢腐蚀速率降至0.017 3mm/a,作用时间为11~13d。 相似文献
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过冷DD3单晶高温合金的净化影响因素及途径 总被引:5,自引:1,他引:4
以特制的复合熔盐作为净化剂在氩气氛保护及循环过热条件下去除DD3单晶高温合金熔体中的异质晶核 ,获得了最大 2 1 0K过冷度。详细探讨了复合熔盐净化机制 ,同时对比分析了纯循环过热和熔融玻璃净化方式对于DD3单晶高温合金获得深过冷的可行性 相似文献
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研究了150 ℃时效条件下,经过360,720以及3 000 h以上时效处理后Sn-Zn-Nd钎料焊点界面组织的变化. 结果表明,焊点在长期时效过程中界面层成分的变化主要由原子的扩散机制主导,随着界面附近各原子浓度的变化,界面层的成分从焊后的单一Cu5Zn8层逐渐转变为成分复杂的Cu-Zn-Sn多元结构. 在时效过程中,由于界面层体积的增加会受到钎料基体的阻碍,因此在界面两侧的晶界处产生了压应力. 这些应力在时效过程中不断累积,当累积到一定程度后,使得金属间化合物层表面出现了孔洞和裂纹,从而导致了焊点性能的恶化. 相似文献