CUI Yan, ZHANG Shao-qing. Effect of SiC Particle Size on Micro-fracture Mechanism of SiCp/Al2O3-Al Composites Synthesized by Oxidative Infiltration of Al Melt[J]. Journal of Materials Engineering, 2000, 0(6): 3-6.
The phases on fracture surface of SiCp/Al2O3-Al composites synthesized by oxidative infiltration of Al melt were analyzed quantitatively using X-ray photoelectron spectrometer for the first time, and then the content of various phase at fracture surface were compared one by one with the content of corresponding phase in the composites determined by metallographic examination.By the comparison, the preference for the crack penetrating various phases of the composites was identified,in turn micro-fracture mechanisms of the composites were revealed quantitatively.It is proved that SiC particle size has a critical influence on the micro-fracture mechanisms of this kind of composites.The tested results of mechanical properties at room and elevated temperature show that, the total level of mechanical properties of the Al2O3-Al matrix composites containing 10μm SiC particle which are.optimized on basis of the above-mentioned analysis of micro-fracture mechanisms, is superior to abroad products of the same kind.
ZHANG Er-lin, JIN Yun-xue, ZENG Song-yan, ZHU Zhao-jun, LI Dong, KANG Qiang. Effect of Carbon Content on the Microstructure of in situ TiC Particulate Titanium Alloy Matrix Composites[J]. Journal of Materials Engineering, 2000, 0(6): 7-12.
TiC particulate titanium alloy matrix composites has been produced with different C content by a reaction synthesis and the phase constitution and the microstructure of the composites have been investigated in detail by XRD, SEM.The results have shown that Ti-6Al-1.8C is composed of Ti and TiC reinforcements that are of two different morphologies: coarse dendritical primary TiC and short bar-shape eutectic TiC.The calculated result of the lattice of TiC from XRD pattern shows that there exists diffraction peak shift of TiC that may be due to the vacancies of C in TiC structure.The effect of C content on the microstructure and the morphology of TiC has also been studied.It has been shown that C content has no influence on the microstructure of matrix.But with the decreasing of C content from 1.98% to 0.39%, the coarse dendrite TiC disappears and only short bar-shape or plate-shape eutectic TiC exists in the composites.
ZHANG Wen-long, FU Wei-hong, WANG De-zun, YAO Zhong-kai. Influence of Hot Extrusion on the Plasticity of SiCW/Al Composites[J]. Journal of Materials Engineering, 2000, 0(6): 13-15.
Hot-extrusion of SiCW/Al composites was realized and tensile fracture surfaces were investigated by means of SEM. The results indicate that the plasticity of SiCW/Al composites can be increased by using hot-extrusion technology. The reason of the increased plasticity of SiCW/Al composites after hot-extrusion is that both the increase of plasticity of the matrix, and directional alignment and breakage of whiskers in the composites.
MEI Zhi, YANG Feng, YAN You-wei, DUAN Han-qiao. A Study on Microstructure of in situ Synthesized TiC Particulates Reinforced Ferrous Matrix Composites[J]. Journal of Materials Engineering, 2000, 0(6): 16-19.
In situ synthesized TiC particulate reinforced ferrous matrix composites with different matrix compositions were manufactured, and their microstructure were investigated by means of analytical transmission electronic telescope. The results show that the matrix microstructure near TiC reinforcements is related with the carbon content of matrix, and a higher carbon content of matrix helps to refrain the formation of Fe2Ti phase.In the matrix containing some molybdenum element, a surrounding structure which is rich in molybdenum element exists between TiC reinforcement and matrix.It improves wettability between matrix and TiC reinforcement, and this helps the TiC reinforcements to distribute in matrix more uniformly.
LIN Jun-pin, ZHANG Yong, CHEN Guo-liang. Microstructures and Properties of Skeleton Reinforced Composite[J]. Journal of Materials Engineering, 2000, 0(6): 20-21.
From the point of view of the microstructure feature, the theoretical analysis confirms that the skeleton reinforced composite has higher volume fraction of reinforcement f and more interfaces A than particulate reinforced composite as both composites have same the structure parameter.The strength of skeleton reinforced composite is the sum of the strength of paticulate reinforced composite and the strength of skeleton as both composites have same f.
ZHANG Wei-fang, XI Nian-sheng, TAO Chun-hu, HAN Jie-cai, DU Shan-yi. Investigation on Reaction Process of Al-TiO2-C-Ti-Fe System[J]. Journal of Materials Engineering, 2000, 0(6): 22-25,41.
The reaction mechanism and kinetic of Al-TiO2-C-Ti-Fe system were studied.The results show that the reaction processes in Al-TiO2-C-Ti-Fe system vary with temperature.While the dominant reactions in high temperature range are the decomposition of intermetallics and the reaction between Ti and C, the reactions in the low temperature range vary greatly with Fe content as following.The dominating reaction in Al-TiO2-C-Ti system is that between Al and Ti.The dominating reactions in the Al-TiO2-C-Ti-20wt%Fe system are those between Al and Ti, Al and Fe, accompanied by a small quantity of reactions between Al and TiO2, Fe and Ti.The dominating reactions in Al-TiO2-C-Ti-50wt%Fe system are those between Fe and Al, Fe and Ti.
YANG Zu-pei, QU Shao-bo, GAO Feng, TIAN Chang-sheng. The Effect of Excess PbO and Excess MgO on Phase Structure and Dielectric Property of PMN-PT Ceramics[J]. Journal of Materials Engineering, 2000, 0(6): 26-29.
0.8PMN-0.2PT powders and ceramics of pure perovskite were sucessfully prepared by molten salt synthesis using mixtures of NaCl and KCl salt.The effect of excess PbO and excess MgO on phase structure and dielectric property of PMN-PT ceramics was studied.The results indicate that excess PbO and excess MgO have a beneficial effect on reducing and even eliminating pyrochlore phase and increasing dielectric constant.The effect of excess MgO is better than that of excess PbO.
RAO Qung-li, WANG Hao-wei, ZHOU Rao-he. Structure Transformations and Property of Electroless Ni-B Coating[J]. Journal of Materials Engineering, 2000, 0(6): 30-33.
A Ni-B coating is prepared by EP with potassium borohydride reducing agent.The as-plating microstructure of coating is confirmed to be a mixture of amorphous and supersaturated solid solution with XRD analysis.The micro-hardness is up to HV1300 after heat treatment.The transformation process of the coating microstructure depends on heat-treatment temperature, and 350℃ is the critical temperature of microstructure transformation.It is found that Ni2B is formed during this transformation process.The factors which influence on hardness of coating are evolution of stress, dissolution of B and formation of Ni3B and Ni2B. And the formation of Ni2B is the key factor.The peaks of micro-hardness curves vary with heat-treatment temperatures, and tend to shorten heat-treatment time with higher temperature.The transformation process becomes more complex when the heat-treatment temperature accesses crystallizing temperature.
XU Long-tang, XU Bin-shi, MA Shi-ning, ZHOU Mei-ling. EPMA Analysis of Brush-plating Ni/nano-SiC Composite Coating[J]. Journal of Materials Engineering, 2000, 0(6): 34-35,12.
In this paper, the composite coating of Ni/nano-SiC was prepared by brush-plating technology. The microhardness of the composite coating were investigated, and the relationship between the main parameters and the microhardness were also discussed. The EPMA was used to analyze the composite coatings’ microstructure, surface morphology and elements distribution. On the basis of experimental results, the mechanism of the codeposition of nano-SiC and Ni was discussed.
YANG Fu-min, JIANG Wen-hui, SUN Xiao-feng, KANG Yu-ping, GUAN Heng-rong. Effect of Si on Microstructure and Mechanical Property of K40S Superalloy[J]. Journal of Materials Engineering, 2000, 0(6): 36-38.
The effect of Si on the microstructure and the stress-rupture property at 815℃/205MPa of K40S superalloy was studied.It is shown that, with the rise of Si addition, interface grows by way of endogeneous growth instead of dendritic interface growth during the alloy solidification ;Si can not only segregate in interdendritic or intergranular greatly, but also dissolve into the matrix noticeably; the appearance of the fracture surface of stress-rupture specimens varies from transcrystalline to interdendritic,and the stress-rupture life decreases.
LIU Qing-suo, ZHAO Lian-cheng, LIN Cheng-xin, GU Nan-ju. The Structures of the Stress Induced εM at Low Stress in Fe-17Mn-10Cr-5Si-4Ni Alloy[J]. Journal of Materials Engineering, 2000, 0(6): 39-41.
By means of TEM and XRD technique,it was studied how the microstructure of stress induced εM in the Fe-17Mn-10Cr-5Si-4Ni alloy changes along with the enhance of stress level at room temperature.At low stress related to the strain less than 3%, the thickness of the mono-variant εM plate is thiner than 5nm; While at higher stress corresponding to exceeded 3% strain, the relatively longer εM plates, which are structured by units arranging along length orientation, are formed.The complex nature of the large εM is determined by the manner of arranging and overlapping of the units.
XIE Yong-hui, LIU Xiao-fang, MAO Wei, LI Xiao-hong, YAN Ming-gao. Effects of TLP Bonded Joint Microstructure of IC-6 Alloy on Its Tensile Property[J]. Journal of Materials Engineering, 2000, 0(6): 42-44.
900℃ tensile property of IC-6 joint TLP bonded using Ni-Based filler metal was studied.Results show that the joint strength does not always increase with increasing bonding time.The joint strength and ductility ware decided by the strength of grain boundaries in the bonding seam,as well as the apperance,amount and distribution of borides formed at the faying surface.In addition, less fractured areas along grain boundaries correspond to higher joint tensile strength and ductility.The borides would fracture owing to brittleness and low coherence with the substrate.γ′ film enclosing the borides would decrease stress concentration to hamper propagation of the cracks.
WEI Ping, LI Jia-rong, ZHONG Zhen-gang, LAO Ri-ling. Effects of Heat Treatment Regime on the Size and Amount of γ′ Phase of DD6 Single Crystal Superalloy[J]. Journal of Materials Engineering, 2000, 0(6): 45-46,12.
The effects of the heat treatment regime on the size and amount of γ′phase of DD6 Ni-Based single crystal superalloy have been investigated.The research results show that the solution temperature has the effects on the size and amount of γ′phase of DD6 single crystal.Aging treatment results in the increasement of the size and amount of γ′ phase of DD6 single crystal, and improvement of regularity of γ′ phase.The first aging treatment has more effects on the size and amount of γ′phase of DD6 than the second aging treatment.
