材料期刊网

INFLUENCE OF MOULD ROTATION ON MACROSEGREGATION IN INGOT

YU Qiuping ZHOU Yaohe Northwestern Polytechnical University , Xi'an , China [Originally published in ACTA METALL SIN (CHINESEEDN) 24 (5) 1988pp B307—B312 , received 27 December 1986 , in revised form 7 December 1987]

金属学报(英文版)

The macrosegregation formation in an ingot and the influence of rotating mould upon it were analysed on the basis of interdendritic flow.When the ingot mould rotates unidirectionally,the centrifugal volume force acts on all inner parts,and when the ingot mould rotates alternately, the tangential alternate force is also formed,and both have various influences on the different modes of interdendritic flow.It is shown that as the ingot mould rotates unidirectionally or alternately with a moderate angular speed,the interdendritic unstable flow may be controlled effectively and the formation of segregation may be restrained.Thus,it seems to be significant for reducing the segregation such as A-type etc.,in the steel ingot.

关键词: ingot , null , null

INFLUENCE OF ZIRCONIUM ON MICROSTRUCTURE AND DAMPING CAPACITY OF ZA27 ALLOY

J.C. Wang , Z.M. Zhang , Y.L. Lu , G.S. Song and G.C. Yang (State Key Laboratory of Solidification Processing , Northwestern Polytechnical University , Xi'an 710072 , China)

金属学报(英文版)

To improve the damping capacities of metals and alloys, the microstructures and damping capacities of ZA27 alloy modified by Zr were studied, and the damping capacities at room tempemture were measured by using cantilever beam techniques. The experiment results show that Zr can refine the Al-rich primary phase and improve the damping Capacities saliently. Compared with the un-modified one, the damping capacity of ZA27 alloy modified by 0.3wt%Zr received 90 percent increment. The high damping capacities are attributed primarily to grain ablement and the increasing of phase interfaces.

关键词: ZA27 alloy , null , null , null

ZA27合金时效过程研究

汤宏群 , 曾建民 , 邹勇志 , 顾红

机械工程材料 doi:10.3969/j.issn.1000-3738.2007.04.020

采用差示扫描量热分析法(DSC)和高温显微分析法分别研究了ZA27合金的等温时效转变过程和加热过程中的共析转变.结果表明:与传统方法相比,采用差示扫描量热分析法研究ZA27合金等温时效转变过程具有快速、准确、制样简单、操作方便等特点;另外,ZA27合金加热过程中的共析转变速度很快,转变首先在晶界处开始,迅速向晶内扩展.

关键词: ZA27合金 , 时效 , 共析转变

铸造Zn-27%Al(ZA27)合金中性介质中的腐蚀行为

施忠良 , 顾明元 , 吴人洁 , 张廷华

腐蚀科学与防护技术

根据盐雾腐蚀试验和常规3%NaCl溶液中ZA27合金腐蚀组织观察和分析,指出:合金化和热处理状态对ZA27合金腐蚀特性有一定影响.ZA27合金腐蚀特点是晶界腐蚀和选择相腐蚀共同作用.选择相腐蚀特点是在试样表面形成许多球状白色锈斑;晶界腐蚀特征是晶界出现明显的腐蚀开裂.

关键词: 铸造Zn-27%Al(ZA27)合金 , null

STUDY ON THE FRACTURE PROCESS OF AN AS CAST Zn 27WT% Al ALLOY

Z.M. Ding and L.M. Zhang Departmentof Material Science and Engineering , Dalian Railway Institute , Dalian 116028 , China

金属学报(英文版)

Thefracture processof an ascast ZA27 alloy under thetensiletest atthe room temperature wasstudied. Theresultsshow thatthecracksof ZA27 alloy form at(α+ η)eutectic phaseand develop bypropagatingalongthe(α+ η) phaseandcuttingthroughthe dendriteαphaseand εphase. Theinfluenceof every phasein ZA27 on thestrength and ductility was ana lyzed.

关键词: SZA27 alloy , null , null

第27卷B辑作者索引

金属学报

Volu扣ne 27SeriesB1991AUTHOR INDEX CCAO Guanghan(曹光旱)············……6一B科6CAo weijie(曹卫恋)..················……5一B32oCAO Yilin(曹益林)··················……6一B443CHANG Xin(常听)···············……1一B48CHE Guang邻n(车广灿)·············一6一B科0CHEN Erbao(陈二保)···············……6一B410CHEN Jia....

关键词:

ZA27合金的微观组织

陈体军 , 郝远 , 孙军 , 狄杰建

中国有色金属学报

用SEM和TEM对金属型铸造并经18个月自然时效的Z A27合金的微观组织进行了观察. 结果表明: ZA27合金凝固的初生相为富Al的树枝状α′相, 随后在α′相周围形成一层富 Zn的包晶β相 , 最后剩余液体发生共晶反应, 共晶β优先依附于包晶β相形核、长大, 而共晶η则在包晶β相间形成一层薄膜, 在有些区域则形成棒状共晶组织; 在随后的冷却及时效过程中 , β发生胞状分解形成规则的共析α+η层片组织或不规则的复杂形状组织, 共析胞以共晶η相为基形核, 并向枝晶中心生长, 使α′相也分解为层片α+η组织, 当其生长被α′中心的连续分解所阻挡时, 致使其芯部形成细小的α+η颗粒组织; 富Cu的ε相存在于所有η相中.

关键词: ZA27合金 , 金属型铸造 , 自然时效 , 微观组织

27SiMn钢连铸坯热塑性研究

孙以春

物理测试

应用Gleeble3800热模拟试验机，针对27SiMn钢连铸坯，进行了热塑性测试。分析了27SiMn试样的显微组织与塑性的关系。研究了测试温度范围内钢的脆化原因。试验结果表明：550~1200℃的脆性温度区域为600~850℃，其断面收缩率ψ=23.0%~50.0%，为指导27SiMn钢的连铸生产提供理论依据。

关键词:

Correlation of mechanical properties in bulk metallic glasses with (27)Al NMR characteristics

Chinese Science Bulletin

We report (27)Al NMR and magnetic susceptibility measurements of Zr and ZrHf-based bulk metallic glasses (BMGs). (27)Al NMR Knight shift shows that there exists a clear correlation between the local electronic properties at Al sites and mechanical properties. In addition, magnetic susceptibility measurements also provide clues on the influence of the electronic states, especially the strong influence of d-orbital characteristics on the mechanical properties of toughness and hardness.

关键词: bulk metallic glass;nuclear magnetic resonance;knight shift;magnetic;susceptibility;mechanical properties;supercooled liquid region;cu amorphous-alloys;electronic-structure;zr;transition;ni;strength

EFFECT OF ANNEALING ON DAMPING CAPACITIES OF AS-CAST ZA27 ALLOY

null , null , null , null

金属学报(英文版)

ZA27 alloy was prepared by casting with permanent mold and then annealed at 250℃ for 1-4h. The damping capacity of the alloy was measured using a testing apparatus based on the cantilever beam technique. It was found that the as-cast ZA27 alloy possesses high damping capacity with the value of 1.3 × 10-3 at 320Hz. After annealed at 250℃ for 1h, the damping capacity decreases to 1.1 × 10-3 and then remains constant even when the annealing time is increased to 4h. The microstructure of the as-cast ZA27 alloy consists of large dendrites of Al-rich primary α-phases, eutectoid (α + η) and nonequilibrium eutectic phases (α + η + ε). After annealing at 250℃ for 1h, the ε phase disappears due to dissolution into the matrix, and the spacing between the flakes of eutectoid increases. The further increase in the annealing time has little effect on the spacing. The damping mechanism of the alloy was discussed considering the thermoelastic damping and defect damping. The value of thermoelastic damping accounts only for 7%-8% in the overall damping in cantilever beam damping measurements and the damping capacity of the ZA27 alloy came mainly from defect damping.

关键词: damping capacity , null , null