漆璇
,
江伯鸿
,
徐祖耀
金属学报
研究了Cu-Zn-Al合金分别经水淬、分级淬火和淬火加时效处理后,马氏体的有序化程度及其和形状记忆效应(SME)之间的关系.有序化程度用一些特定马氏体线对的面间距差值△d来表征,线对指数应满足下式:(h_1~2-h_2~2)/3=(k_2~2-k_1~2)/n(对9R马氏体n=1,对18R马氏体N=4).分级淬火得到M18R马氏体,其△d值随分级等温时间而增大,与形状恢复能力η的提高一致.水淬得到M9R马氏体,刚淬火状态有相当大的△d和良好的SME,但室温停留使△d和η均下降,TEM点阵条纹象证实这是淬火过饱和空位在(001)_M基面聚集、降低有序程度的结果.淬火后高温时效(180℃)或过高的分级温度都会使△d和η下降,这与α相析出以及可能发生的溶质原子偏聚有关,都会降低有序程度.
关键词:
Cu-Zn-Al合金
,
martensite
,
ordering
,
shape memory effect
WU Jianxin JIANG Bohong XU Zuyao (T.Y.Hsu) Shanghai Jiaotong University
,
Shanghai
,
China Associate Professor
,
Dept.of Materials Science and Engineering
,
Shanghai Jiaotong University
,
Shanghai
,
China
金属学报(英文版)
The effect of grain size and ordering of the parent phase on the critical points of thermoelastic martensitic transformation in Cu-25.62 Zn-3.97 Al-0.0018 B(wt-%)shape memory alloy has been investigated.Based on the thermodynamics of phase transformation,a linear rela- tionship between the starting temperature of martensitic transformation and the reciprocal of the square root of grain size is obtained,i.e.M_s temperature rises with increasing grain size. It shows a good agreement with the results of electric resistance measurement.Applying the Landau's theory,a quantitative relationship between M_s and the ordering parameter of the parent phase is set up,which is well confirmed by the results of X-ray diffraction and electric resistance measurement.The activation energy of the ordering process in the parent phase of the alloy is calculated to be 46 kJ/mol.
关键词:
Cu-Zu-Al
,
null
,
null
,
null
,
null
QI Xuan JIANG Bohong XU Zuyao(T.Y.HSU) Shanghai Jiaotong University
,
Shanghai.China Qi Xuan
,
Dept.Marter.Sci.and Eng.
,
Shanghai Jiaotong University
,
Shanghai
,
China
金属学报(英文版)
The correlation between the shape memory effect(SME)and the ordering degree in martensite formed through various heat-treatment processes,e.g.ice water quenching, step-quenching and aging etc.,has been studied in a Cu-26Zn-4Al alloy.The martensite or- dering degree is estimated by △d,the spacing difference of some pairs of diffracting planes with indices satisfying a relation of(h_1~2-h_2~2)/3=(k_2~2-k_1~2)/n(n=1 for 9R martensite,n=4 for 18R martensite).M 18R martensite is obtained from step-quenching,in which the value of △d increases with the holding duration of step-quenching,and the shape recovery rate η increases synchronouslly.9R martensite is obtained from direct water-quenching,the value of △d is quite large and SME is also good at just quenching state.But both △d and η decrease continuously with aging time at room temperature.This stabilization phe- nomenon of martensite is explained by the observation of TEM lattice fringe image,and it may be attributed to the clustering of quenched-in supersaturated vacancies at (001)_M close-packed plane in martensite and decreasing the ordering degree.A reduction in △d and η occuring in the specimens on step-quenching or aging at higher temperature, which may be related to the precipitation of the α-phase and the enrichment of solute atoms, decreases the ordering degree.
关键词:
Cu-Zn-Al alloy
,
null
,
null
,
null
,
null
周彪
,
程西云
,
彭美华
,
张建锋
,
严茂伟
人工晶体学报
对碳纳米管(MWNTs)进行化学镀镍处理制备镀镍碳纳米管(Ni/MWNTs),在500±0.5℃条件下对Ni/MWNTs进行热处理;采用磁诱导/冰模板定型复合方式将热处理Ni/MWNTs添加到壳聚糖溶液中,冷冻干燥形成MWNTs有序排列的镀镍碳纳米管-壳聚糖(Ni/MWNTs-CHI)多孔结构;将多孔结构浸入环氧树脂-固化剂-丙酮系统混合液,真空干燥处理10 h制得序列化镀镍碳纳米管-环氧树脂(Ni/MWNTs-EP)复合材料.利用分析型扫描电镜、振动样品磁强计对Ni/MWNTs进行表征.利用SEM观察了序列化Ni/MWNTs-CHI多孔显微结构.采用微机控制电子万能试验机测试了复合材料力学性能.结果表明:热处理工艺能够均匀化所镀镍层,使热处理后Ni/MWNTs饱和磁化强度(Ms)提高17±1倍;SEM发现多孔结构内局部MWNTs呈有序化排列;当MWNTs含量为2wt％时,序列化Ni/MWNTs-EP材料较MWNTs-EP材料断裂拉伸力提高了49.94％.
关键词:
碳纳米管
,
热处理
,
磁学性质
,
冰模板
,
序列化
余方新
,
程建奕
,
沈斌
中国有色金属学报
通过透射电镜和高分辨透射电镜研究 Cu-0.69Cr-0.10Zr-0.02Mg 合金在450℃早期时效的析出贯序。研究表明：合金在450℃早期时效的析出贯序为过饱和固溶体→溶质偏聚→FCC富Cr的GP区(Ⅰ)→FCC有序富Cr的GP区(Ⅱ)→BCC有序富Cr相。在脱溶演变过程中，析出相和基体之间的界面由完全共格界面向共格-半共格界面转变，位向关系由立方-立方向Nishiyama-Wassermann位向关系转变。共格界面的形成有利于FCC富Cr相的形成。富Cr析出相的有序化加速析出进程，并有利于BCC相的形成，促进了Nishiyama-Wassermann位向关系的发展。
关键词:
Cu-Cr-Zr-Mg合金
,
析出贯序
,
时效
,
有序化
,
共格界面
,
位向关系
莫远科
,
张志豪
,
谢建新
,
潘洪江
金属学报
doi:10.11900/0412.1961.2015.00661
采用弯曲实验,拉伸实验,SEM,TEM和EBSD等手段,研究了再结晶退火对高硅电工钢冷轧带材组织、有序结构、力学性能和冷轧成形性能的影响.结果表明,冷轧试样经800～1200℃保温1h再结晶退火随炉缓冷后,室温塑性大幅下降,可弯曲角度均由冷轧试样的150°下降至50°左右,且二次冷轧出现严重的边裂;提高再结晶退火后的空冷或油淬温度、冷却速率可显著提高试样的室温塑性,1000℃保温1h再结晶退火后,900℃油淬试样的可弯曲角度增大至175°左右,拉伸断后伸长率由随炉缓冷试样的0.2％提高至5.2％,且二次冷轧基本不出现边裂;提高再结晶退火后的冷却温度和速率显著提高试样的室温塑性的原因是试样的有序相尺寸明显减小,例如,有序相畴尺寸可从600℃以下油淬试样的约5μm分别减小至700℃油淬试样的小于50 nm和900℃油淬试样的小于25 nm.
关键词:
高硅电工钢
,
冷轧
,
再结晶退火
,
有序度
,
力学性能
