航空材料学报

INFLUENCE OF CAST TEMPERATURE-RATE PARAMETERS ON MICROSTRUCTURES OF CARBON-FREE SINGLE CRYSTAL SUPERALLOYS

E. A. Gleshova, E. N. Karblov, V. V. Glarsimov

1993, 13(4): 1-14.

[Abstract](1440) [PDF 3625KB](132)

Abstract:
This work has investigated the microstructures of two single crystal superalloys, DD3 and ЖС36,producted under diffrent cast parameters in two D. S equipment У BHK-8П and ISP2/Ⅲ-DS,which possess different temperature gradient on solidifying solid-liqUid interface. The results show that the single crystal microstructure obtained in У BHK-8П furnace has finer dendrite size, more dispersive phase structure and less microporosity than that in ISP2/Ⅲ-DS furnace due to about 50% higher temperature gradient in the former.

INVESTIGATION OF HYDROGEN PERMEATION BEHAVIOUR IN TWO Fe-Ni-Cr-BASED SUPERALLOYS

Xu Jian sun Xiukui Liu Qingquan Chin Wenxiu Li Yiyi

1993, 13(4): 15-20.

[Abstract](1386) [PDF 379KB](151)

Abstract:
In this work, a gaseous permeation technique was employed to measure the hydrogen permeability and diffusivity for two Fe-Ni-Cr-based alloys,GH35A and GH761, over the temperature range of 210 to 430℃. A attempt was made to understand the effects of microstructure variation in the alloys on hydrogen permeation behaviour. The results indicated that, over the range of experimental temperature, hydrogen permeation behaviour in the two alloys obeyed Arrhenius relationship and that the hydrogen permeability and diffusivity for the GH35A alloy are not sensitive to the mierostructure variation, but for GH761 alloy the values Ф and D in the aged condition are all slightly lower than those in the solid solution treatment.

THE MICROSTRUCTURES OF Fe-10Ni-14Co STEELS CONTAINING C, Cr AND Mo

Zhong Bingwen, Ling Bin, Gu Baozhu, Zhong Ping

1993, 13(4): 21-27.

[Abstract](1192) [PDF 1192KB](194)

Abstract:
The microstructures of the steels containing two carbons contents have been investigated by means of TEM. The results show that, the presence of twinning martensite should be attributed to alloying elements addition in steel, and the austenitizing temperature, and cooling rate are not important factors. The alloy carbide found in 830℃ quenched and tempered at 510℃ conditions was indentified as Mo2C. The orientation relatiorship between α and Mo2C follows Pitsch-Schrader rule. Some pieces of reverted austinite in quenched and tempered(510℃ 5h) conditions were revealed.

THE RELATION BETWEEN THE STRENGTH OF CARBON FIBRE-REINFORCED PLASTICS AND THE PROPERTIES OF REINRORCED CARBON FIBRES

G. M. Guniyaev

1993, 13(4): 28-33.

[Abstract](1465) [PDF 418KB](157)

Abstract:
This paper reaserches for the relations between the strength of carbon fibre-reinforced plastics and the properties of reinrorced carbon fibres. The conclusion shows that the relations of them were close, and according to various working conditions of materials in structure, when we decide the requirement of carbon fibres, we should comprehensively consider all kinds of factors critical to their properties.

RADAR. ABSORBENT STRUCTURE MATERIALS

Liang Bin

1993, 13(4): 34-43.

[Abstract](1557) [PDF 526KB](283)

Abstract:
In the paper the research of Radar Absorbent Structure Materials is introducted. By theoretical design and CAD, a kind of wide frequency-width Radar Absorbent Structure Plate named"trap"and a kind of wide frequency-width Radar Absorbent Honeycomb Sandwich Material are obtained.

RESEARCH ON DIFFUSION BONDING OF Si₃N₄ USING RAPIDLY SOLIDIFIED Al-BASED INTERLAYER

Zhai Yang, Ren Jialie

1993, 13(4): 44-51.

[Abstract](1386) [PDF 1198KB](165)

Abstract:
In this poper, a new rapidly solidified(RS)Al-based interlayer material has been developed. The properties of this interlayer and the diffusion bonding of Si3N4 with it have been investigated. The results show that:After rapid solidification, the Al-based interlayer has smaller grain, more homogeneous composition, lower melting point and higher hardness. At the same diffusion bonding parameter, the shear strength of joint using RS Al-based interlayer is remarkably higher than that of using normally solidified (NS)Al-based interlayer. The max shear strength of the joint with RS Al-based interlayer is 50MPa,at the diffusion bonding parameters of 475℃×30min×15MPa. With the increase in temperature of diffusion bonding, the shear strength of joint decreases remarkably. The result of fracture analyzing shows that:All joints are broken near by the interface. The In-rich phase on the interface is the weak region of joint. With the in crease in temperature of diffusion bonding, the size of In-rich phase increases and the strenhth of joint decreases. The joining mechanism of diffusion bonding of Si3N4 using RS Al-based interlayer is that:Ti and Al diffuse toward interface、react with Si3N4 and form TiN、AlN ere interface phases.

EFFECT OF THICKNESS ON FATIGUE CRACK GROWTH UNDER CONSTANT AMPLITUDE LOADING AND FLIGHT SIMULATION LOADING

S. J. Zhang, Y. G. Zhu, X. Y. Huang, S. L. Liu, H. Ouyang, Z. W. Yue, A. M. Luo

1993, 13(4): 52-61.

[Abstract](1438) [PDF 675KB](153)

Abstract:
Fatigue crack growth tests were conducted in 7475-T7351 Al alloy with different thickness specimens. From constant amplitude loading test with lower stress ratio and flight simulation loading tests a significant thickness effect was observed. Crack growth life prediction was carried out using some famous models. It was found that Newman’s model has the capability to predict thickness effect, generalized modified Willenborg model is not able to consider thickness effect even by adjusting constraint coefficient. The physical reason of thickness effect and the modeling consideration are two of the important subjects for successful crack analysis.

1993 Vol. 13, No. 4