Mi Guofa, Li Qingchun. Investigation on Microstructure and Thermal-resistant Behavior of Rapidly Solidified Al-8wt% Cr Alloy[J]. Journal of Materials Engineering, 1997, 0(5): 3-5.
In the present paper rapidly solidified ribbons of Al-8wt% Cr alloy are prepared using rapid cooling apparatus with monoroller.By XRD,TEM,electronic probe and energy spectrum analysis,and as-annealed as-quenched microstructures were studied.The microhardness of the alloy was measured with microhardnessmeter after different annealing temperature.The study shows that the different regions of the rapidly solidified alloys along the thickness of the ribbon have significantly different microstructures,the second phase caused by annealing is distinguished asθ-Al7Cr,by means of measurement of microhardness,the soften temperature is determined in the range of300～350℃.
Huang Hongfa, Yan Hai, Tao Chunhu. Characterizing and Prediction of 30CrMnSiNi2A Fatigue Crack Initiation Time[J]. Journal of Materials Engineering, 1997, 0(5): 6-8,19.
The a-t data from fracture surface are analysed by an equation of crack growth rate that is often used in durability.Weibull distribution is used to describe the distribution of reference crack initiation time.Equivalent initial faults sizes distribution characterizing a group of specimens with the same configuration under spectrum loading is finished.From the results,the TTCI distribution probabilities about different stress levels and crack lengths could be obtained.
Cao Peng, He Yuehui, Huang Baiyun, Liu Wensheng. In Situ Observation of Fracture Process for Ti Al-base Alloy with Fully Lamellar Microstructure[J]. Journal of Materials Engineering, 1997, 0(5): 9-11.
In situ observation of the tensile fracture process for Ti-33Al-3Cr-0.5Mo(wt%) alloy with fully microstructure was conducted in this work.Fully lamellar Ti Al alloy exhibits high fracture toughness.The crack bifurcation results in crack-tip blunting during tensile process.The formation of shear ligaments by mismatched crack planes might lead to an enhancement in the fracture toughness.The fractograghic analyses show that the translamellar fracture and cleavage of interfaces are the two dominant fracture modes.
Cao Jingxia, Sun Fusheng, Cao Chunxiao, Gao Yang. High Cycle Fatigue Properties and Fracture Features of Ti-25Al-10Nb-3V-1Mo[J]. Journal of Materials Engineering, 1997, 0(5): 12-14.
The high cycle fatigue S-N curves of Ti-25Al-10Nb-3V-1Mo alloy at650℃ are determined.Some samples are also tested following preexposure at 650℃ and 700℃ respectively.The results show that Ti-25Al-10Nb-3V-1Mo alloy has good fatigue strength which can reach the need of rotor components.The comparison of high cycle properties between smooth and notched specimens indicats that the notched sensitivity of this alloy is high and the sensitivity is getting higher with the stress increasing.In this study,fatigue fracture features are observed in SEM.The fatigue crack initiation and propergation,as well as the micro-stress state are all discussed and analysed in details.
Ding Chuanfu, Li Qian. Influence of Corrosion Environment and Coldworked Holes on Fatigue Properties of 300M Ultra-high Strength Steel[J]. Journal of Materials Engineering, 1997, 0(5): 15-19.
The corrosion fatigue properties of 300M ultra-high strength steel on three state of specimens are investigatd in laboratory air and in 3.5% NaCl water solution.The experimental results show that an intersection is existed between the S-N curves of coldworked holes in saltwater and no-extrusion in air at f=10Hz.The strengening effects are acted mainly above the stress level of the intersection.The environment effects are acted mainly below the stress level of the intersection.The environment effects are afunction as the stress levels.The environment effects are more marked according as the stress levels decrease.The strengthening effects caused environment effects to decrease and fatigue strength to increase.
Xing Zhanping, Yu Liguo, Guo Jianting. Study on the Room Toughening Mechanism in the NiAl-TiC in Situ Composite[J]. Journal of Materials Engineering, 1997, 0(5): 20-22.
Fracture toughness of NiAl-TiC in situ composites was measured using single-edge notched three-point bend specimens.The composites were fabricated by a hot pressing aidedexothermic synthesis(HPES) technique.The results show that the average fracture toughness ofthe composite was 8.9MPa·m1/2,50% higher than that of monolithic NiAl.From fracture surface and crack propagation path analysis,crack deflection was rationalized as the predominanttoughening mechanisms.
Yuan Jianjun, Liu Zhien, Xue Mingjun, Ying Chengqi. A Study of the Interface Optimization of Glass-elake/Fpoxy-resin Composites[J]. Journal of Materials Engineering, 1997, 0(5): 23-25,36.
The surface changes of glass flake before and after modified,the interface and the mechanical properties of composites were examined by means of ESCA,IR,SEM and electric universal test machine,by brining test the anti-permeability of composites was also studied.The results showed that a layer of organic molecule was formed on the glass flake surface after modified,and so the combination of glass flake with epoxy resin was optimized,the impermeability and the mechanical properties of composites were also improved.
Yin Jingzhi. A Study of a Test Method for the Coefficient of Moisture Expansion of Composite Materials[J]. Journal of Materials Engineering, 1997, 0(5): 26-27.
A test method for determining the coefficient of moisture expansion(CME) of composite materials was proposed in this paper.Some factors that would influence the determination of CME of composite materials were discussed.Experimental procedures were performed on the studies of moisture expansion of composites T300/3231.The results showed that the method presented here can be u sed for the determining of CME of composite materials.
Zhang Zheng, Gao Jianlin, Zhong Qunpeng, Li Shi'an. Application of Artificial Neural Network on Diagnosis of Cold Brittle Fracture[J]. Journal of Materials Engineering, 1997, 0(5): 28-30.
In this paper,the relation between cold brittle fracture and some factors such as ctystall structure,strength,stress concentration,grain size,loading rate and temperature,is studied by applying artificial neural network.
Zhang Yong. Effect of Mineralizer on Mullite Formation and Lithofacies Microstructure in Mould-shell[J]. Journal of Materials Engineering, 1997, 0(5): 31-33.
In this paper,the effect of five types of mineralizer and various sintering temperature on the extent of forming mullite in a mould-shell for single crystel superalloy blades has been studied,also the effect of mineralizer composition on the lithofacies microstrucfure at three sintering temperature has been reseached.
Wang Xingye. Measurements on the Diameter and the Specific Surface Area of Silica Particles in a Silica Gel[J]. Journal of Materials Engineering, 1997, 0(5): 34-36.
The diameter and the specific surface area of silica particles,which have great effect on properties of silica gel,should act as a performance index.The methods which are determining the diameter and the specific surface area of silica particles had been discussed.
Ma Sheng, Tan Yongning, Li Xunhua. Study on Ni3Al Based High Temperature Alloy Mix Particle of Carbonide[J]. Journal of Materials Engineering, 1997, 0(5): 37-38.
The Process on Ni3Al based high temperature alloy (IC6alloy) mix TiC particle used for special method was studied,and obseved the variations of structure,characteristic of distribution of TiC particle.The results show that process and structure was regulated,it can make TiC particle even variate in structure of IC6 alloy,improve property of IC6 alloy become possible.The main problem of process was discussed.
Fan Jianzhong, Yao Zhongkai, Guo Hong, Li Yichun, Shi Likai, Zhang Shaoming. Effect of Fabricating Parameters on the SiCp Distribution State in SiCp/Al Composites by Powder Metallurgy[J]. Journal of Materials Engineering, 1997, 0(5): 39-42.
Effect of fabricating parameters on the SiCp distribution state in SiCp/Al composites by powder metallurgy was investigated systematically at both macro-and micro-mixed levels.The results showed that the good macro-blending mixture was easily obtained during powders mixing procedure,however,the micro-blending degree of the mixture was comparatively bad.And there was the best mixing time during the dry mixing operation.And the extrusion procedure much improved the micro-blending degree of SiC particles.
Chai Shichang, Li Yuren, Wang Tianzhen, Hou Shue, Yu Guifu. Effect of Compaction Technique on Properties of RSP Al-Li Alloys[J]. Journal of Materials Engineering, 1997, 0(5): 43-44,47.
The Press and its holding of compaction have positive effect on ductility of RSP Al-Li alloys and effect on strength is not obvious.
Hu Yanguang, Yu Rongli, Tian Yongjiang. Failure Analysis of the Compressor Crosshead Bolt[J]. Journal of Materials Engineering, 1997, 0(5): 45-47.
The chemical composition of the material,machanical properties,macro-micro-fractography and loading condition of the crosshead bolt of the compressor have been studied.The fatigue fracture mode is determined.The main cause of the fatigue fracture is found.The prevention effective measures are proposed.
Ruan Ruxiang. Titanium Silicon Carbide (Ti3SiC2)—— A Remarkable High Temperature Material[J]. Journal of Materials Engineering, 1997, 0(5): 48-49.
Titanium silicon carbide has excellent electrical and thermal conductivity,high strength of up to 1300℃,good oxidation and thermal shock resistance and thus has been considered as candidate material for high temperature applications.The present paper described the structure,processing,and properties of titanium silicon carbide.The potential of further applications was also discussed.
