董毅许云波吴迪
金属学报
通过单道次压缩及连续冷却实验, 研究了变形温度(810-720 ℃)对具有超细原始奥氏体晶粒的含Nb双相钢显微组织的影响. 实验结果表明: 实验钢最终组织为铁素体加马氏体的双相组织. 压缩过程中, 实验钢应力-应变曲线上出现峰值, 且峰值应力随变形温度的降低先增大后减小; 随着变形温度的降低, 铁素体的含量先增大再减小, 但增减幅度不大, 在最低变形温度(720 ℃)时, 铁素体晶粒尺寸降低到2.8 μm, 弥散分布于铁素体晶界上的马氏体含量达到22.7%; 随着变形温度的增加, 铁素体晶粒硬度减小, 最低可降至230 GPa; EBSD取向分析显示, 随着变形温度的降低, 组织中小角度晶界增多.
关键词:
含Nb钢
,
ultrafine grain
,
deformed in low temperature region
,
orientation map of grain
W. Chen
,
D. Fergson and H. Ferguson (Dynamic Systems Inc. Poestenkill
,
NY 12140
,
USA)
金属学报(英文版)
There is a considerable interest in developing methods for processing of materials with ultrafine grain si- zes. Widely used methods in refining microstructure are severe/intense plastic deformation techniques, such as torsion straining, equal channel angular (ECA) pressing/extrusion,and accumulative roll bonding (ARB) technique.While the torsion technique has been available for decades,a new torsion system has been developed at DSI for simulation of complex stress states such as combination of shear and compression or shear and tension stress states. The equal channel angular pressing technique is ma- inly used for production of ultrafine grain aluminum alloys,which is aimed at develoment of high strain rate superplasticity.The accumulative roll bonding technique has been applied for the rolling of both aluminum alloy and steels to produce ultrafine gained materials. Three different types of hot compression deformation methods, each with a different number of deforma- tion axis, are introduced in this paper. They are single axis deformation, two axis deformation and three axis deformation.The single axis deformation has us or little restraint such as plane strain type testing and axisymmetric compression testing, the two - axis deformation can be fully restrained or un- restrained, and the three - axis deformation has no restraint. The two - axis restrainsd compression deformation techopue is recommended for loboratory side after comparing the single - axis and the three - axis deformation techniques since the bulk volume of the two - axis restraint compression speci- men can be easily machined into mechanical testing speciments for mechanical property measurement and other studies,and the technique can be aplied to studies of any metallic materials.
关键词:
ultrafine grain
,
null
D. Ferguon
,
W. N. Chen and H. Ferguson (Dynamic Systems Inc. Poestenkill
,
NY 12140
,
USA)
金属学报(英文版)
Ultrafine grain size is often achieved by severe plastic deformation. A few techniques have been devel- oped to achieve severe plastic deformation,such as equal channel angular (ECA ) processing, torsion, and accumulative roll bonding (ARB) techmpues. This paper will introduce a moftiaxis deformation technique which can achieve essentially unlimited strain with constant deformation volume. The mul- tiaxis deformation can be fully restrained or unrestrained.The bulk volume of a multiaxis restraint compression specimen can be easily machined into mechanical testing specimens for mechanical property measurement and other studies.
关键词:
ultrafine grain
,
null
,
null
Z.M. Zhang
,
*
,
C.J. Xu
,
J.C. Wang
金属学报(英文版)
Ultrafine-grained pure aluminum L2 with a mean grain size of 1.0μm was produced by equal channel angular pressing (ECAP) and annealing at 150℃ for 2h. Damping behavior of the alloy was measured using a dynamic mechanical thermal analyzer. The alloy had an excellent damping capacity Q-1 with the ambient value being 9.8×l0-3 at 1.0Hz when the strain amplitude was 2.0×l0-5. The damping behavior of the alloy showed a non-linear damping variation tendency, that is, with an increase in temperature and a decrease of frequency, the damping capacity of the alloy increased. The damping capacity increased with the strain amplitude when the strain amplitude was less than 4.6×l0-5. When the strain amplitude was higher than 4.6×10-5, the damping capacity became a constant and independent of strain amplitude. The high damping capacity was attributed to dislocation unpinning and a drag of dislocation on pinning points.
关键词:
ECAP
,
超细晶
,
阻尼
,
铝合金
汪程鹏
,
李付国
,
李景辉
稀有金属材料与工程
剪挤(SE)成形方法作为一种剧烈塑性变形方法被提出来用于成形薄壁管件,为评估该方法的细晶能力和强化效果,以纯铜管件为研究对象,对其进行4道次的SE成形.金相观察发现剪挤成形的组织得到很好的细化,同时伴随晶粒取向的增大现象.TEM研究表明,纯铜SE细化主要是由剪应变引起的位错细化机制为主,以应变局部化动态再结晶为辅的复合细化机制.此外,成形后材料的HV硬度1070 MPa较成形前材料的硬度400 MPa有很大的提高,该变化主要是位错强化引起的.
关键词:
剧烈塑性变形
,
超细晶
,
铜
,
挤压
,
微观组织
方锳泽
,
周小平
,
徐峰
材料热处理学报
为研究搅拌摩擦加工作用机理,对铝合金表面热喷涂铝基涂层进行了4道次搅拌摩擦加工.应用SEM、EDS、TEM和显微硬度测试对加工前后的涂层进行分析.结果表明,涂层经过搅拌摩擦加工后,原本层叠状、有孔隙组织通过形变诱导位错切割机制,首先形成滑移带,同时位错密度不断增加并聚集成小角度晶界,然后逐渐转变成大角度晶界,将晶粒分解细化,最终演变成致密的超细等轴晶,尺寸达到200 nm以下.涂层和基体之间发生了相互融合,涂层和基体间的间隙消失.基体中的合金元素向涂层扩散.搅拌摩擦加工后,涂层显微硬度从62 HV上升到269 HV.
关键词:
铝合金
,
搅拌摩擦加工
,
形变诱导位错切割
,
热喷涂
,
超细晶
穆罕默德·奥斯曼
,
郭宝
,
佟运祥
,
陈枫
,
田兵
,
李莉
,
郑玉峰
稀有金属材料与工程
详细介绍了块状超细晶TiNi基形状记忆合金的研究进展,包括其制备工艺与显微组织、马氏体相变行为、力学性能和形状记忆特性以及超弹性性能,并介绍了其在医学和工程领域的实际应用,最后探讨了块状超细晶TiNi基形状记忆合金今后的研究发展方向.
关键词:
TiNi形状记忆合金
,
大塑性变形
,
超细晶粒
,
形状记忆效应
李敏
,
刘静
,
姜庆伟
金属学报
doi:10.11900/0412.1961.2016.00475
利用TEM观察累积叠轧法(ARB)制备的超细晶Cu的微观结构,在IBTC-5000单轴疲劳试验机上对制备态及不同温度退火态的ARB-Cu进行单向静态拉伸实验,通过SEM观察力学测试后试样的断口形貌。结果表明：在实验温度范围内,退火处理均使ARB-Cu的屈服强度和抗拉强度下降,当退火温度低于再结晶温度时,ARB-Cu的屈服强度和抗拉强度均随退火温度的升高而升高;当退火温度高于再结晶温度时,其强度迅速下降。当退火温度为200 ℃时,ARB-Cu的屈服强度和抗拉强度达到退火态最大值。随退火温度的升高,ARB-Cu的晶粒尺寸略微增大,晶粒分布逐渐由制备态的单峰分布转变为双峰分布,断口形貌显示出塑性逐渐增加的趋势。退火处理有助于ARB材料焊合界面结合强度的提高,退火温度越高,焊合界面结合性能越好。焊合界面经历的叠轧道次越多,其结合效率越高,其理论计算公式为E=(1-0.5n)×100%。
关键词:
超细晶
,
累积叠轧
,
退火
,
微观结构
,
断口形貌
肖平安
,
陈超
,
曹杰义
,
宋建勇
,
李志华
材料研究学报
doi:10.11901/1005.3093.2015.564
以极细TiH2粉末为原料,采用压制/真空烧结的方法制备细晶或者超细晶钛,并通过HIP进一步提高钛的致密度以保障力学性能;同时还研究了添加少量Y对钛制品的影响.通过拉伸试验评价了所得钛制品的力学行为,并对显微组织和断口开展了系统分析.研究结果表明,由极细Ti2粉末分解而来的钛粉具有优秀的烧结性能,在600～900℃发生快速致密化,当烧结温度≥1000℃时制品的相对致密度＞97％.随着烧结温度的提高,制品的晶粒逐步长大,但是在1150℃下真空烧结2h后平均晶粒度仍然小于10mm.拉伸试验结果表明,纯钛制品的抗拉强度在700～1032 MPa之间,而含Y钛制品的抗拉强度＞750MPa,且延伸率为8％～10％.TiH2分解对所获Ti粉起始晶粒度的遗传性影响和钛粉中固溶态H对晶粒合并长大的阻碍作用,是利用极细TiH2粉末短流程制备细晶或者超细晶钛的机理.
关键词:
金属材料
,
氢化钛
,
钛
,
超细晶
,
力学性能
