LI Jihong
,
NING Xiaoguang
,
YE Hengqiang (Laboratory of Atomic Imaging of Solids
,
Institute of Metal Research
,
Chinese Academy of Sciences
,
Shenyang) SHEN Baoluo
,
LI Wei
,
TU Mingjing (Chengdu University of Science and Technology
,
Chengdu
,
China)Manuscript received 18 April 1995
金属学报(英文版)
The stability of K_2O·8TiO_2 whiskers and the microstructures of the interfaces in K_2O·8TiO_2 whisker reinforced ZL109 aluminum composites under different heat treatment conditions were investigated by means of transmission electron microscopy(TEM) , mostly by high resolution TEM( HRTEM). It was found that K_2O·8TiO_2 whiskers were not very stable.The edge of the whiskers decomposed and a TiO interfacial layer formed during the process of fabricating K_2O·8TiO_2/ ZL109Al composite,and so the interior with increasing temperature and time of heatreatment. Two kinds of interfacial microstructures between the whiskers and the matrix were characterized; one was the TiO layer and the other was a nano scale amorphous transition layer. A few MgAl_2O_4 particles were also observed at the whisker/ matrix interfaces.
关键词:
: potassium titanate whisker
,
null
,
null
PA N JinChangsha Institute of Technology
,
ChinaLI Jihong
,
NING Xiaoguang
,
YE HengqiangLab. of Atomic Imaging of Solids
,
Institute of Metal Research
,
Chinese Academy of Sciences. Shenyang
,
China Manuscript received 28 February
,
1994
金属学报(英文版)
A newly developed whisker K_(2)O 6TiO_(2) reinforced 6061 Al composite was prepared by squeeze casting process. The flexural strength of the composite is 518MPa, and decreases to 490 M Pa after T6 treatment.The hardness of the composite also shows the similar change while T6 treating. The results of HRTEMobservation may explaine this property change. It was considered that there is a continuous TiO layer at the whisker-matrix interface, which is easily to react with the segregated Mg and to form MgTi_(2)O_(4), MgAl_(2)O_(4). The thickening of TiO layer after T6 treatment is the main reason resulting in strength degradation of composite.
关键词:
potassium titanate. whisker
,
null
,
null
Y.D.Xiao
,
W.X.Li
,
D.Jacovkis
,
M.T.Clavaguera-Mora
,
J.Rodriguez-Viejo
,
N.Clavaguera
金属学报(英文版)
Rapidly solidified Al87Ni7Cu3Nd3 metallic glasses, prepared by using melt spinning, were treated under both isothermal and non-isothermal regime. The amorphous rib-bon and the annealed samples were closely examined by means of differential scan-ning calorimetric, conventional X-ray diffraction and high resolution transmission electron microscopy with selected-area electron diffraction, with special interest in pri-mary crystallization into α-Al nanocrystalline particles, in order to understand struc-tural characteristics of Al-based amorphous/nanocrystalline alloys, and nucleation and grain growth mechanism on the nanometer scale during primary crystallization. The results show that, the as-prepared ribbons are fully amorphous and homogeneous in the micron scale, but contain high density of quenched-in clusters or crystallite embryos. Primary crystallization mainly leads to formation of two-phase mixture of α-Al crystal and residual amorphous phase. The annealed ribbons exposed isother-mally at 110℃ for 5, 130 minutes and heated continuously up to less than 310℃ at 40℃/min consist of large amount of α-Al fec crystal nanoparticles dispersed uni-formly in an amorphous matrix. However, a very little amount of finer orthorhombic Al3Ni intermetalics particles exist in the annealed ribbons heated up to 310℃. During primary crystallization, the leading kinetic mechanics to impede growth of the α-Al crustal is soft impinaement, instead of geometric impinqement.
关键词:
rapid solidification
,
null
,
null
