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Effects of Additional Elements on Microstructure and Precipitation Behaviour in Rapidly Solidified Al-Ti Base Alloys

Won-Wook Park , Chul-Jin Choi and Bong-Sun You (Dept. of Materials Processing , Korea Institute of Machinery and Metals , 66 Sangnam-Dong , Changwon , Kyungnam , Korea 641-010)(To whom correspondence should be addressed)

材料科学技术(英文)

Rapidly solidified Al-Ti base alloys were prepared by melt spinning at the cooling rate about 107 K/s. The melt-spun ribbons were used to observe the dricrostructures after heat treatment.In the supersaturated Al-Tl-Si alloy, age hardening occurred after 1 h anneal in the temperature range of 4000~500℃, which seems to be attributed to the precipitation of metastable Ll2- (Al,Si)3Ti phase. However. the microhardness was relatively low because of the low v/o and the insufflcient stability of precipitates. Thus. Cr was added to Al-Ti-Si alloys in order to stabilize the microstructures and to increase the v/o of precipitate5. As a result. the alIoys containing Cr were evaluated to possess the improved properties at the service temperature.

关键词:

R & D ACTIVITIES ON AEROSPACE MATERIALS IN KOREA

H.M. Kim(Korea Institute of Machinery and Materials , Korea Manuscript received 26 August 1996)

金属学报(英文版)

This paper briefly reviews research and development programs in Korean aerospace industry,with an emphasis on aircraft materials technology. International collaborations in these areas are outlined and the R & D activities are highlighted against the background of the national economy.It is shown that the investment from government agencies and large enterprises has led to healthy development of aerospace materials industries in Korea.

关键词: :R & D , null , null , null

Nanocrystal Model for Liquid Metals and Amorphous Metals

X.L. Tian C.W. Zhan J.X. Hou X.C. Chen J.J. Sun

材料科学技术(英文)

A nanocrystal model for liquid metals and amorphous metals has been developed. With the nanocrystal model, the broadening peak profiles (BPPs) of Cu, Al, Al65Cu20Fe15 alloy, Cu70Ni30 alloy and Fe50Si50 alloy were gained by broadening the X-ray diffraction (XRD) peaks of a crystal lattice. By comparing the BPPs with the XRD intensity curves measured on the liquid metals, it is found that the BPPs are closely in agreement with the XRD intensity curves, respectively, except the Fe50Si50 alloy. Therefore, the nanocrystal model can be used to determine if the atomic cluster structure of the liquid metal is similar to the structure of its crystal lattice.

关键词: Liquid metal , Atomic Cluster , Structure , Crystal Lattice

Twinnability Predication for fcc Metals

B.Q. Li

材料科学技术(英文)

Inherent twinnability of face-centered-cubic (fcc) metals was analyzed based on the direct competition between twinning partial dislocation nucleation and trailing partial dislocation nucleation, with which the twinnability of fcc metals can be simply expressed as function of the stacking-fault energy, the unstable stacking-fault energy, and the unstable twinning-fault energy of fcc metals. The predicted twinnability ranking matched well with former experimental results and provided a physical insight to understand twinnability from crystallographic orientation and fault energy parameters.

关键词: Deformation twinning

Twinnability Predication for fcc Metals

材料科学技术(英文)

Inherent twinnability of face-centered-cubic (fcc) metals was analyzed based on the direct competition between twinning partial dislocation nucleation and trailing partial dislocation nucleation, with which the twinnability of fcc metals can be simply expressed as function of the stacking-fault energy, the unstable stacking-fault energy, and the unstable twinning-fault energy of fcc metals. The predicted twinnability ranking matched well with former experimental results and provided a physical insight to understand twinnability from crystallographic orientation and fault energy parameters.

关键词: Deformation twinning;fcc metals;Twinnability;deformation twins;nanocrystalline aluminum;plastic-deformation;low;temperatures;single crystals;crack-tip;alloys;nucleation;copper

DISSIPATIVE QUANTUM TUNNELING IN METALS

Communications in Theoretical Physics

The influence of a bath consisting of both conduction electrons and Debye phonons on quantum tunneling in metals is studied by the perturbation approach developed by the authors. We find that the renormalized tunneling parameter and the condition of localization transition are modified in comparison with the results of a bath consisting of conduction electrons.

关键词: system

ADVANCED SYNTHESIS OF LIGHT METALS

F.H. Froes(IMAP , University of Idaho , Moscow , ID 838443026 , USA Manuscript received 26 August 1996)

金属学报(英文版)

The synthesis, processing and mechanical properties of the light metals, aluminum,magnesium and titanium Produced by advanced techniques are reviewed. Synthesis techniques to be addressed will include rapid solidification, spray deposition, mechanical alloying, plasma Processing and vapor deposition.

关键词: :synthesis/processing , null , null , null , null , null , null , null , null , null , null

Tearing Toughness of Ductile Metals

Cui-Hong Li , Qi-Qiang Duan , Zhe-Feng Zhang

金属学报(英文版) doi:10.1007/s40195-016-0371-8

A new parameter, i.e., tearing toughness, was employed to characterize the mechanical properties of some ductile metals (Cu, Cu-2 wt% Be, Cu-Al alloys, and some steels) by using three-leg trousers tearing tests. The experimental results demonstrate that their tearing toughness is not a physical constant and shows a close relationship with the materials’ types and microstructures. It can be inferred that the tearing toughness of different ductile metals has their respective variation range, expectantly, and may be represented by the comprehensive mechanical properties of strength and ductility for various ductile materials.

关键词: Ductile , metals , Strength , Ductility , Tearing , toughness

Fusion Equation of Metals

HONC Yongyan Zhejiang Institute of Technology , Hangzhou , China.

材料科学技术(英文)

An expression of initial slope of melting curve of pure metals was obtained as follows: (dT_m/dP)_o=T_(mo)/c, where c=1.09 (N_(at))~(5/3)z~(-1/3), the unit of c is GPa, N_(at) is the atomic concentra- tion (in 10~(28) m~(-3)), z is the valence, T_(mo) is the melting temperature (in k) of metal under one atmosphere. The calculated results for thirty-one metals agree well with experiments. It has also been proved that by using the free electron model of melting, the fusion equation of metals is Simon equation (T_m/T_(mo))q=1+(p/d). Two parameters q and d, which have to fit with experiments in Simon's empirical equation, now can be predicted theoretically, e.g. for Mg, giving q=1.56, d=7.88GPa, the calculated melting curve in a fairly wide pressure range (0~60GPa) is shown to be close to the experimental one.

关键词: melting curve of metals , null

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