热处理对ZCuSn3Zn8Pb6Ni1FeCo合金组织性能的影响

利用真空离心铸造方法制备的ZCuSn3Zn8Pb6Ni1FeCo合金试样,经850～900℃下保温1.0～3.0h后水淬固溶处理,随后在时效处理温度450、500、550和600℃下分别保温4h,用XRD、SEM、HREM分析研究该合金时效工艺对组织性能的影响。结果表明:ZCuSn3Zn8Pb6Ni1FeCo合金以α-{Cu,Sn}为基体,存在有硬脆δ-Cu10Sn3相,强化析出相主要有α-Fe、γ-Fe、CoCu2Sn、Fe3Co7、Fe4Zn9等,铅以单质形式析出;与铸态相比合金经过固溶处理后抗拉强度提高33.3%,伸长率提高55.1%;合金经500℃时效4h处理,抗拉强度与常规固溶处理相比提高了8.3%,伸长率却下降了55.1%;ZCuSn3Zn8Pb6Ni1FeCo合金中强化析出相Fe4Zn9和基体Cu形成半共格关系;α-Fe和基体Cu形成完全共格关系;ZCuSn3Zn8Pb6Ni1FeCo合金经固溶处理后,共格强化效果与Orwan公式计算结果非常接近,而固溶强化、空位强化和细晶强化的贡献甚微。

高强高导Cu-Cr-Zr系合金的研究现状

从合金成分设计、析出相结构和制备技术三方面综述了高强高导Cu-Cr-Zr系合金的研究现状。在分析多种元素对合金强度影响的基础上,重点讨论了稀土元素的作用,适量稀土的加入能同时提高合金的硬度和电导率。Cu-Cr-Zr系合金的析出相主要是Cr和CuxZr(x=3,4,5)相,且合金在470℃时效4h形成有序的原子排列,其化合物类型为CrCu2(Zr,Mg)。固溶形变时效强化技术和快速凝固技术与常规固溶时效处理相比都能大大提高合金的综合性能。该类合金今后应向多元微合金化方向发展,尚待解决的主要问题是Zr、稀土等易烧损元素的熔炼较难控制。

高强铝合金热冲压成形技术研究进展

为了解决高强铝合金板料冷成形时塑性差、容易出现破裂及回弹大、影响尺寸精度的问题,发展起来了一种高强铝合金固溶–热冲压–淬火–时效一体化新工艺。该工艺将热成形与热处理有机地结合在一起,将固溶后的热板料快速转移到模具中成形,并立即完成模内淬火,最后通过时效处理来提高其强度。首先总结了高强铝合金热冲压成形技术的最新研究进展,重点介绍了铝合金热冲压成形工艺试验方面的研究成果,详细说明了铝合金热成形时影响成形性能的因素和实现固溶时效强化的工艺方法,最后从摩擦机理和界面传热的角度总结了铝合金热冲压模具技术方面的研究进展。

Effects of on-line solution and off-line heat treatment on microstructure and hardness of die-cast AZ91D alloy

The effects of on-line solution, off-line solution and aging heat treatment on the microstructure and hardness of the die-cast AZ91D alloys were investigated. Brinell hardness of die-cast AZ91D alloy increases through on-line solution and off-line aging treatment but decreases after off-line solution treatment. By X-ray diffractometry, optical microscopy, differential thermal analysis, scanning electron microscopy and X-ray energy dispersive spectroscopy, it is found that the microstructures of the die-cast AZ91D magnesium alloy before and after on-line solution and off-line aging are similar, consisting of α-Mg and β-Al12Mg17. The precipitation of Al element is prevented by on-line solution so that the effect of solid solution strengthening is enhanced. The β-Al12Mg17 phases precipitate from supersaturated Mg solid solution after off-line aging treatment, and lead to microstructure refinement of AZ91D alloy, so the effect of precipitation hardening is enhanced. The β-Al12Mg17 phases dissolve in the substructure after off-line solution treatment, which leads to that the grain boundary strengthening phase is reduced significantly and the hardness of die cast AZ91D is reduced.

Enhanced strengthening by two-step progressive solution and aging treatment in AM50-4%(Zn,Y) magnesium alloy

AM50-4%(Zn,Y)alloy with a Zn/Y mole ratio of6:1was subjected to thermal analysis,and the results were used for designing a two-step progressive solution treatment process.The effects of solution and aging treatments on the microstructure and mechanical properties of the AM50-4%(Zn,Y)alloy were investigated using OM,XRD,SEM/EDS,TEM,tensile test and hardness test.The experimental results demonstrated that the two-step progressive solution treatment could make theΦandβphases sufficiently dissolve into the matrix which possessed higher supersaturated degree of the dissolved solute compared with the one-step solution treatment.This resulted in a certain enhancement of the precipitation strengthening effect during the subsequent aging process.The precipitation of theФphase had a greater impact on the comprehensive mechanical properties of the alloy thanβphase precipitation when the aging treatment was performed at180℃.The peak aging strength of the AM50-4%(Zn,Y)alloy which was subjected to the two-step progressive solution treatment process(345℃for16h and375℃for6h)was obtained after the aging treatment at180℃for12h.

α+β两相钛合金的动态压缩性能对抗弹性能的影响分析

以研究钛合金材料动态压缩性能对抗弹性能的影响为目的,选用TC4、TC6、TC11三种不同强度级别的α+β两相钛合金为研究对象,采用动态压缩试验、准静态拉伸试验以及5.8 mm口径实弹靶试测试等方法,对材料微观组织、力学性能、动态压缩性能、弹坑形貌进行了对比分析。结果显示,TC4、TC6和TC11三种α+β两相钛合金经过固溶时效热处理后,TC11钛合金的拉伸强度和动态压缩强度最高,分别达到1258 MPa和1973 MPa,采用12 mm厚度的三种钛合金靶板进行靶试测试,对垂直入射的5.8 mm口径钢芯弹均进行了有效防护,TC11钛合金开坑深度2.4 mm,开坑尺寸7.5 mm×5.5 mm,均小于其他两种钛合金靶板的弹坑尺寸,对钢芯弹的侵彻有更好的防护作用。针对普通钢芯弹的防护,材料的动态压缩性能与其抗弹性能存在对应关系,动态压缩强度越高,临界断裂应变εcr越大,受冲击过程吸收的能量越多,抗弹性能越好。