Fuxing YIN
,
Nanju GU (Hebei Institute of Technology
,
Tianin 300132
,
China)T.Shigematsu
,
N.Nakanishi(Faculty of Science
,
Konan University Kobe 658
,
Japan)Y.Osawa
,
A.Sato(National Research Institute of Metals
,
Tsukuba 305
,
Japan)
材料科学技术（英文）
Amorphization of Mn carbides by rapid quenching method has been proved to be unsuccessful.By mechanical milling in the present work, amorphous phases have been formed in the perovskitetype Mn3AlC compound. The transformation process from crystalline to amorphous phase was found to be milling time controlled, and 10 h is a critical period for the macroscopically single amorphous phase to form. It has been clarified that the redistribution of C atoms is an instinctive factor for amorphous phase to nucleate, and the atomic configuration in the amorphous phase is changed much in longer milling that different crystallizing behaviours have been caused. With X-ray diffraction and differential scanning calorimetry (DSC) results, an atomic configuration transition model is considered for the structures of the amorphous phases changed during milling.
关键词:
WADSWORTH Jeffrey and FLUSS Michael(Chemistry and Materials Science Directorate
,
Lawrence Livermore National Laboratory
,
Livermore
,
CA 94551)
金属学报(英文版)
The role of the National Laboratories is summarized from the era of post World War II to the present time. The U.S. federal government policy for the National Laboratories and its influence on their materials science infrastructure is reviewed with respect to .determining overall research strategies, various initiatives to interact with industry (especially in recent years),building facilities that serve the nation, and developing leading edge research in the materials sciences. Despite reductions in support for research in the U.S. in recent years, and uncertainties regarding the specific policies for Research &Development (R&D) in the U.S., there are strong roles for materials research at the National Laboratories. These roles will be centered on the abilities of the National Laboratories to field multidisciplinary teams, the use of unique cutting edge facilities, a focus on areas of strength within each of the labs,increased teaming and partnerships, and the selection of motivated research areas. It is hoped that such teaming opportunities will include new alliances with China, in a manner similar, perhaps, to those recently achieved between the U.S. and other countries.
关键词:
: U.S. Materials Science. U.S. National Laboratories and Facilities
,
null
S.H.O
材料科学技术（英文）
The magnetic property of soft magnetic metals and alloys depends strongly on the crystallographic orientation. In automated equipment for orientation research. the intensity for drawing up the pole figure is measured in detail. The present research shows that the accurate pole figure can be drawn up without measuring concretely the intensity. For directional Si steel sheet the measuring step may be 4 similar to 5 degrees. In this paper the experimental equation for defocusing correction was derived from the experimental data in different specimens with random orientation.
关键词:
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
MA Zongyi YAO Zhongkai Harbin Institute of Technology
,
Harbin
,
China
金属学报(英文版)
The SiC_w/Al composite prepared by squeeze casting has a combination of superior room temperature specific strength and modulus together with excellent thermal properties.The extrusion can make an improvement on the strength and ductility of the composite from 582 MPa as squeeze casted up to 639 MPa,and on the transformation from isotropic to the anisotropic structure.This seems to be explained by the orientation of whiskers and the densification of dislocations in matrix.TEM observation indicates that the stacking fault is the usual planar defect on the SiC_w surface. composite;;SiC whisker;;Al alloy;;microstructure
关键词:
composite
,
null
,
null
,
null
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
