Jianbo YU
,
Zhongming REN
金属学报(英文版)
doi:10.1016/S1006-7191(08)60068-X
The effects of electromagnetic vibration on the grain refinement in directional solidification were investigated. It was found that the electromagnetic vibration applied in the melt not only can refine grains remarkably but also can enhance both tensile strength and ductility values of Al-6%Si alloy. SEM graphs show that coarse dendrite structure was broken up into a somewhat globular structure, and the morphology of eutectic silicon was changed from flaky to fibrous under electromagnetic vibration treatment. The refine mechanism under electromagnetic vibration was discussed.
关键词:
Electromagnetic vibration
,
null
,
null
,
null
Jianbo YU
,
Zhongming REN
,
Weili REN
,
Kang DENG
,
Yunbo ZHONG
金属学报(英文版)
doi:10.1016/S1006-7191(08)60088-5
An electromagnetic vibration was generated by simultaneously imposing a strong static magnetic field (up to 10 T) and an alternative electricity current to the metal. Its effects on the solidification structure of eutectic Al-Si alloy have been investigated experimentally. It is found that the eutectic structure has been refined by solely imposing high magnetic field while it is coarsened under the electromagnetic vibration. Furthermore, polyhedral Si grains and non-dendritic α-Al appeared when the electromagnetic vibration strength was strong enough. The refining of eutectic structure is attributed to the decrease of diffusion coefficient caused by the strong magnetic field. The coarseness of eutectic structure may be attributed to the convection caused by electromagnetic vibration. Strong convection may break co-operative growth of eutectic phases to form polyhedral Si grains and non-dendritic α-Al.
关键词:
Strong magnetic field
,
null
,
null
,
null
,
null
Zhongming REN
,
Hui WANG
,
Kang DENG
,
Kuangdi XU
材料科学技术（英文）
The solidification structure of Bi-3 wt pct Mn alloy grown up in the semisolid zone under the influence of a static magnetic field (up to 1.0 T) and the relation of the magnetic property with the solidification structure have been investigated experimentally. It was shown that the primary phase MnBi crystals in the alloy aligned and oriented along the direction of the applied magnetic field. The orientating tendency and the average length of the elongated MnBi crystals increased with the increase of the applied field and the solidification time. Moreover, the remanence of the alloy along the aligned direction of the MnBi phase in the case of solidification with a magnetic field was apparently anisotropic and nearly double of that without the magnetic field. This indicated that the MnBi crystals oriented and aligned along their easy magnetization axis. A model was proposed to explain the alignment and orientation growth of the MnBi crystals in a magnetic field in terms of the magnetic anisotropy of the crystals and the magnetic interaction between them.
关键词:
Magnetic field
,
null
,
null
,
null
张麦仓
,
董建新
,
曾燕屏
,
谢锡善
,
罗子健
金属学报
利用热力耦合有限元程序FORMT,对PM René 95合金中等尺寸(外径尺寸约为630 mm)涡轮盘的等温锻造工艺进行了模拟式设计.结果表明,采用TZM钼基合金模具,在1050℃以接近10-3s.的应变速率进行闭式模锻和开式模锻,模具材料均能满足使用要求,且开式模锻设备最大载荷不超过31×103kN;采用K21合金模具,在1000℃以相同条件等温成形,模具材料因变形热效应及边界摩擦引起温升而失效且所需设备吨位相对较大.
关键词:
PM
,
null
,
null
,
null
张麦仓
,
董建新
,
曾燕屏
,
谢锡善
,
罗子健
金属学报
doi:10.3321/j.issn:0412-1961.2002.10.022
利用热力耦合有限元程序FORMT,对PM René 95合金中等尺寸(外径尺寸约为630 mm)涡轮盘的等温锻造工艺进行了模拟式设计.结果表明,采用TZM钼基合金模具,在1050℃以接近10-3s.的应变速率进行闭式模锻和开式模锻,模具材料均能满足使用要求,且开式模锻设备最大载荷不超过31×103kN;采用K21合金模具,在1000℃以相同条件等温成形,模具材料因变形热效应及边界摩擦引起温升而失效且所需设备吨位相对较大.
关键词:
PM René 95合金,等温锻造,热力耦合有限元,模拟式工艺设计
付锐
,
陈希春
,
任昊
,
冯涤
航空材料学报
doi:10.3969/j.issn.1005-5053.2011.3.002
自行设计开发了适合工业化生产高纯净,低偏析,无宏观缺陷铸锭的电渣重熔连续定向凝固技术(ESR-CDS)的设备和工艺,利用该技术成功制备了直径为φ150mm的René88DT合金定向凝周铸锭.采用XRD测试了定向凝固柱状晶的生长取向,结果表明,ESR-CDS René88DT铸锭柱状晶择优生长方向为<100>系晶向;ERS-CDS铸锭与传统ESR铸锭相比,枝晶组织生长方向保持一致,二次枝晶臂均匀细小,元素偏析程度低,且晶间一次析出相呈颗粒状,尺寸细小;等温热压缩实验结果表明,ESR-CDS René88DT合金热压缩试样在1100℃,0.0-50.1s-1应变速率下可达到70%以上压缩变形量并获得均匀细小的动态再结晶组织;ESR-CDS René88DT合金铸锭经等温锻造制备出了φ170mm×73mm的饼坯件,锻压变形量超过70%,饼坯件除上下两端的变形死区外均发生了动态再结晶,晶粒尺寸约50μm.
关键词:
电渣重熔连续定向凝固
,
热变形
,
动态再结晶
李晓
,
董建新
,
张丽娜
,
张麦仓
,
胡尧和
,
谢锡善
,
国为民
金属学报
经不同固溶时效处理的PM René 95合金于650℃分别在蠕变、保载5和90 s疲劳载荷条件下进行了裂纹扩展速率实验.结果表明,相同热处理制度下,疲劳保载时间越长,裂纹扩展速率越高;相同载荷条件下,增加一次高温固溶并缓冷,有利于降低合金的裂纹扩展速率,且固溶温度越高裂纹扩展速率越低;1200℃一次固溶缓冷并于1160℃二次固溶热处理比1140℃一次固溶的裂纹扩展速率约降低一个数量级;基体晶粒尺寸适当加大,强化相粒子γ′c数量增加、形状趋于田字形,有利于降低裂纹扩展速率.
关键词:
René
,
null
,
null
李晓
,
董建新
,
张丽娜
,
张麦仓
,
胡尧和
,
谢锡善
,
国为民
金属学报
doi:10.3321/j.issn:0412-1961.2001.10.012
经不同固溶时效处理的PM René 95合金于650℃分别在蠕变、保载5和90 s疲劳载荷条件下进行了裂纹扩展速率实验.结果表明,相同热处理制度下,疲劳保载时间越长,裂纹扩展速率越高;相同载荷条件下,增加一次高温固溶并缓冷,有利于降低合金的裂纹扩展速率,且固溶温度越高裂纹扩展速率越低;1200℃一次固溶缓冷并于1160℃二次固溶热处理比1140℃一次固溶的裂纹扩展速率约降低一个数量级;基体晶粒尺寸适当加大,强化相粒子γ′c数量增加、形状趋于田字形,有利于降低裂纹扩展速率.
关键词:
René 95粉末高温合金,裂纹扩展速率,热处理
