航空材料学报

1997, 17(3): 1-1.

[Abstract](1334) [PDF 42KB](90)

Abstract:

Ram Kossowsky

1997, 17(3): 2-10.

[Abstract](1280) [PDF 328KB](309)

Abstract:
Metal matrix composites,MMC,have undergone extensive research and development in the past thirty years,world wide.In spite of this large effort,MMC materials have not been widely adapted for commercial use,and have been sparsely adapted in military systems.The reasons are mainly in the high cost of manufacturing and in the relatively low reliability and large fluctuations in properties. The purpose of this review is to bring to focus the major issues facing development of MMC materials.We begin with a review of the common matrix materials and common reinforcements.The former are limited to aluminum and to titanium alloys.Reinforcements are discussed in terms of particulate,whiskers and fibers.We then review basic design considerations,with emphasis on the choices facing the designer in terms of optimal matrix chemistry,interfacial reactions,differential thermal expansion,and the effects of dominant deformation mechanisms.In terms of titanium matrix composites,the argument is advanced that these materials could not compete with superalloys until the range of temperature of use is increased above 750℃.However,current alloy technologies indicates that no titanium alloy could survive in air at above 680℃ without adequate protective coatings. Next we review consolidation of MMC,including most recent work in European laboratories.The presentation concludes with summaries of recent data,and outlook for the future.

INFLUENCES OF MODIFICATION AND REFINEMENT ON THE STRUCTURE AND MECHANICAL PROPERTIES OF CASTABLE Al/SiC_p COMPOSITE

Gui Manchang, Wang Dianbin, Yuan Guangjiang, Wu Jiejun, Yan Minggao

1997, 17(3): 11-16.

[Abstract](1400) [PDF 271KB](218)

Abstract:
The influences of modification and refinement treatment on the structure and the mechanical properties of 15vol% SiC particles reinforced Al-Si cast composite produced by stirring-cast technique were studied. Experimental results showed that, due to the addition of modification or refinement elements, the changes in the structure of the composite were identical with that of un-reinforced matrix alloy. Modification treatment can change eutectic silicon morphology from flake or needle to fiber, and refinement treatment can obviously refine αAl grain in the SiC particles reinforced composite. Modification and refinement treatment can significantly increase the mechanical properties of the composite. The tensile strength increase by 8% through single refinement treatment, meanwhile simultaneous modification and refinement treatment have the strength increase by 14%.

STUDY ON RHEOLOGICAL BEHAVIOUR OF Al-6wt%Cu BASE SiC GRAIN COMPOSITE SLURRY

Qi Xiumei, Ma Xuezhu

1997, 17(3): 17-21.

[Abstract](1393) [PDF 192KB](237)

Abstract:
In this paper,the rheologicul behaviour of Al-6wt%Cu based SiC grain composite in solid-liquid coexistence zone is studied under the guidence of rheological theory.The composite is obtained by means of stirring.From the result of study,it is found that the rheological behaviour of the composite in solid-liquid coexistence zone can be described by series of arrangement of Hooke model,Bigham model and Kelvin model.Rheological parameters,such sa G,η and τS can be estimated on the basis of the associated modelsl.As the result of the addition of SiC grains the rheological parameters increase to various degrees.At the temperature close to the liquidus,the addition of SiC grain increases the quantity of solid effectively and makes it difficult to be deformed.

INVESTIGATION ON THE PRESSURELESS INFILTRATING PROCESS FOR THE FABRICATION OF Al/Al₂O₃ COMPOSITES

Yan Yue, Peng Yingguo, Zhang Shaoqing

1997, 17(3): 22-26.

[Abstract](1501) [PDF 240KB](343)

Abstract:
Capillary-induced melt infiltration is an attractive method of fabricating Al/Al2O3 composites. The electrical resistance technique was used to follow the perform infiltration process. The complete curve consists of an incubation stage and an infiltration stage. During the infiltration period, the infiltration length was proportional to the square root of infiltration time. Qualitative agreement of theory with experimental results of the infiltration stage has been found.

AGING BEHAVIOUR OF SiC_W/Al/6061Al COMPOSITE

Liu Qiuyun, Fei Weidong, Yao Zhongkai

1997, 17(3): 27-32.

[Abstract](1315) [PDF 259KB](160)

Abstract:
The aging kinetics of 6061Al alloy and SiCW/6061Al composite aged at 170℃,190℃ and 220℃ were studied.The effects of peak aging temperatures on the properties for 6061Al alloy and SiCW/6061Al composite were investigated.The results indicated that the Young's modulus of 6061Al alloy exhibited no considerable change,the yield strength and ultimate tensile strength decreased slightly with the peak aging temperature increasing.However,the Young's modulus,yield strength and ultimate tensile strength of SiCW/6061Al composite decreased obviously with the peak aging temperature increased.

PRELIMINARY STUDY ON THE EFFECTS OF THE INTERFACE STATES ON THE FRACTURE CHARACTERISTICS OF SiC_P/7075Al COMPOSITE

Guo Hong, Shi Likai, Zhang Shaoming

1997, 17(3): 33-38.

[Abstract](1394) [PDF 246KB](148)

Abstract:
A SEM equipped with a tensile apparatus is used to observe in-situ the tensile process of SiCP/7075Al fabricated by PM and the fracture micrograph.A TEM is also used to observe the interface states of the composite.The results show that the binding states of the interface directly effect the fracture characteristics of the composite.

MICROSTRUCTURAL STUDY ON INTERFACE OF B/Al COMPOSITES

Peng Yingguo, Zhang Shaoqing, Yan Yue, Sun Changyi

1997, 17(3): 39-43.

[Abstract](1433) [PDF 208KB](234)

Abstract:
The interfacial microstructures of the B/Al composites have been investigated with transmission electron microscope and X-ray energy dispersive spectrometer. It is revealed that the B4C coating layer has excellent bonding with both the boron fiber and the aluminum alloy matrix, except for very few Al4C3 phases occur in the B4C-Al interface. The coating layer consists of B4C fine crystallites and free graphite clusters. The active element in the Al alloy, Mg, was detected with higher density in the coating layer than in the matrix near the interface. The B4C coating layer with free graphite clusters has successfully restrained the element diffusion between the fiber and matrix.

KINETIC MODEL OF REACTION SYNTHESIS OF TiC IN Al/TiC

Zhang Erlin, Yang Bo, Zeng Songyan, Li Qingchun, Ma Mingzhen

1997, 17(3): 44-50.

[Abstract](1443) [PDF 252KB](232)

Abstract:
A mathematical kinetic model of the reaction process to synthesis TiC particles in Al-Ti-C system has been builted,and a reaction rate expression is developed in this article based on the following mechanism:a Ti-rich Al-Ti complex layer is formed around carbon particles and titanium atoms diffuse from melt,across the layer,to react with carbon to form TiC;the TiC particles precipitate out of the melt and diffuse all over the melt.The calculated results have been shown that there were four major effect factors:the temperature of the system,the total aluminum content of the preform,the thickness of the titanium-rich layer and the size of carbon particle.To decrease the aluminum content,the thickness of titanium-rich layer and the size of carbon particle and to increase the temperature accelerate the reaction rate and reduce the complete reaction time.

MICROSTRUCTURE AND PROPERTIES OF NEODYMIDE PARTICULATE REINFORCED TITANIUM MATRIX COMPOSITES

Li Siqing, Liu Ruimin, Ma Jimin, Cao Chunxiao

1997, 17(3): 51-56.

[Abstract](1230) [PDF 232KB](215)

Abstract:
The microstructure and properties of in-situ neodymide particulate reinforced Ti-6Al-4.5Sn-3.5Zr-0.5Mo-0.7Nb-0.35Si-0.6C(wt%) alloy based composites, produced by conventional ingot metallurgy process, have been investigated in this paper. The particulate shape is spherical or ellipsoidal. The average particulate diameter is ～7μm, the inter-particulate spacing is ～40μm. Incoherent reinforced particulates are uniformly distributed within Ti matrix. They are composed of many very fine polycrystallines (～10nm), and primarily contain neodymium, tin and oxygen. The room temperature and elevated temperature tensile, creep and creep rupture properties of the heat treated composites are tested. The test results show that the composite heat treated at 1065℃/0.5h/FAC+1000℃/1h/AC+700℃/4h/AC have attrative comprehensive mechanical properties. The failure in the composites of tensile and creep rupture is typical ductile fracture. Cracks are observed in some neodymide particulates. Crack propagating from cracking particulate into the matrix has not been observed. 

EFFECT OF THERMAL CYCLING TREATMENT ON MICROYIELD BEHAVIOR OF A SiC_p/Al COMPOSITE

Li Yichun, Fan Jianzhong, Zhang Kui, Zhang Shaoming, Shi Likai, Wu Gaohui, Sun Dongli, Yang Dezhuang

1997, 17(3): 57-62.

[Abstract](1336) [PDF 402KB](161)

Abstract:
An aluminum alloy(6061) matrix composite reinforced with 35% volume fraction of SiC particles was fabricated by squeeze casting method.The SiC particles is angular.The microyield behavior of the composite was investigated,and the effect of different thermal cycling treatment on the microyield behaviors of the composite was studied.Based on TEM and HREM observation of microstructure,the mechanism of microyield behavior in the SiCp/6061 composite was analyzed.Results indicate that the microyield behavior of the SiCp/6061 composite can be described by Brown-Lukens's theory which explained satisfactorily that of aluminum alloys and other light alloys,and is affected greatly by the different thermal cycling treatment.Thermal cycling treatment affects mainly the thermal mismatch stress and the density of movable dislocations in the matrix.

1997 Vol. 17, No. 3