PANG Li-jia, SUN Guang-fei, CHEN Ju-fang, LIANG Jia-huan, ZHANG Jin-biao, LI Wen-an. Crystallization Behavior and Magnetic Properties of Pr2Fe14B/α-Fe Nanocomposite Magnets[J]. Journal of Materials Engineering, 2007, 0(1): 3-6.
Pr2Fe14 B/α-Fe nanocomposite magnetic powders were prepared by melt-spinning and heat-treatment. The microstructure and crystallization behavior were studied by X-ray diffraction (XRD), differential thermal analysis (DTA), and vibrating sample magnetometer (VSM). It is found that the precipitating temperature of α-Fe is sensitive to heating-up rate for melt-spun Pr2Fe14B/α-Fe powders, which can make the precipitating temperature of α-Fe and Pr2Fe14B close by raising the heating up rate. But it is impossible to find a temperature to precipitate two phases at the same time. The metastable phase Pr2Fe23B3 occurs at 963K for as-spun (Pr8.2Fe86.1B5.70.99Zr1 alloys, which deteriorates the magnetic properties. Both extending time and raising the temperature of heat-treatment for crystallization can decompose the metastable phase. After an optimum heat-treatment, the magnetic property of the materials is much better than that of as-spun Pr2Fe14 B/α-Fe powders.
GU Li-xin, JIN Jian-jun. Effects of Tempering Temperature on Microstructure and Mechanical Properties of 1Cr15Ni4Mo3N Steel[J]. Journal of Materials Engineering, 2007, 0(1): 7-10.
The effect of tempering temperature on microstructure and mechanical properties of 1Cr15Ni4Mo3N steel was studied. The results showed that the lath martensite with high density of dislocation and the formation of fine particles M2C dispersive and distributed coherent with the matrix were responsible to the high strength of the steel. The highest strength and the lowest impact toughness were gained after tempering at the temperature about 470℃.
ZHANG Qing-ling, WANG Qing-ru, LI Xing-wu. Materials Selection Analysis for Titanium Alloy Fasteners in Aviation Industry[J]. Journal of Materials Engineering, 2007, 0(1): 11-14,18.
Analysis was made on the application status, materials characteristics and manufacturing technology for three types titanium alloy fasteners. The results showed that the production cost was the lowest for cold deformation hardened BT16 alloy fastener; thermal upset and vacuum solution heat treated Ti-6Al-4V fastener had the lowest density with the highest strength and fatigue property; the β-titanium alloy fasteners had inferior overall properties to those made of BT16 and Ti-6Al-4V alloys, however, their cold upset rivets can be used when necessary.
LIU Hao, LI Ke-zhi, LI He-jun, LU Jin-hua, ZHAI Yan-qiang. Effects of Heat Treatment Temperature on Mechanical Properties of Mesophase Pitch-based C/C Composites[J]. Journal of Materials Engineering, 2007, 0(1): 15-18.
The effects of final heat treatment temperature on the microstructure, mechanical properties and fractured surface image of mesophase pitch-based 2D C/C composites were studied by three-point bending, XRD and SEM test, and the fracture mechanism was investigated. The results show that the graphitization degree and microcrystal size (Lc) increase, interlayer distance (d002) decrease with the increase of final heat treatment temperature of the C/C composites. The interface bonding strength weakens with the increase of heat treatment temperature. The flexural strength of composites after heat treatment is lower than that of untreated, the fracture characters of composites are changed from the brittle fracture to like-tough.
XIAO Yang, ZHANG Xin-ming. Fracture Mechanism Analysis of Mg-9Gd-4Y-0.6Zr Alloy from -196℃ to 400℃[J]. Journal of Materials Engineering, 2007, 0(1): 19-24.
The fractography of Mg-9Gd-4Y-0.6Zr alloy specimens which were tensioned at different temperatures was observed by optical and scanning electron microscopy, respectively. The results showed that different slip systems were activated at different temperatures, which was responsible for varied deformation mechanism and fracture mechanism. At 25℃, the number of enabled slip systems were few and only slip systems on basal plane were activated, and transgranular cleavage fracture was observed. At -196℃,the number of enabled slip systems increased, prismatic slips maybe occurred and low-temperature plasticity phenomenon happened, while fracture mechanism was microviod coalescence fracture. At 250, 300℃ and 350℃, multisystem slips on basal planes, prismatic planes and pyramidal planes were activated in this alloy, while fracture mechanism was also microviod coalescence fracture. At 400℃, recrystallization happened and grain-boundary sliding in new fine recrystallized grains could deform easily,which was called coarse-grain superplasticity phenomenon, and intergranular shear fracture took place.
LUO Fei, PANG Xiao-lu, GAO Ke-wei, YANG Hui-sheng, WANG Yan-bin. Effects of Radio Frequency Power on Mechanical Properties and Wear Resistance of Chromium Oxide Thin Films[J]. Journal of Materials Engineering, 2007, 0(1): 25-28.
Chromium oxide thin films were deposited on 45 steel substrate by reactive magnetron sputtering. The microstructure was characterized by X-ray diffractometer. The Tribo-Indentor(Hysitron) test system was used to investigate the surface morphology and hardness of the thin films. Wear resistance of the films was measured on the UMT micromechanics test system. The effect of radio frequency(RF) power on the mechanical properties and wear resistance was studied. The result showed that films were composed of Cr2O3 in low RF power. Big particles on the surface and wear volume increased and the hardness decreased with the increase of RF power, the wear resistance of the chromium oxide thin films decreased.
CHAI Cheng-wen, LU Min-xu, LI Xing-wu, ZHANG Guo-an. Effects of Imidazoline Based Inhibitor on Morphology and Mechanical Properties of CO2 Corrosion Scales of Carbon Steel[J]. Journal of Materials Engineering, 2007, 0(1): 29-33,36.
The inhibition efficiency of modified imidazoline based inhibitor on the surface of corroded X65 steel in produced water was studied by using autoclave. The surface and cross-section morphology and microstructure of the CO2 corrosion scales with and without inhibitor were investigated by means of SEM. Mechanical properties of the scales were measured by nano-indentation and shear testing. The results indicate that the inhibitor inhibits the corrosion of X65 steel effectively with an inhibition efficiency above 90% under 75℃. The mechanical properties of the scales, including Young’s modulus, microhardness, shear strength between the scales and substrate, were not improved by adding inhibitor. Inhibitor inhibits the corrosion reactions of X65 steel by the geometric blocking effect of inhibitive substance adsorbed on the metal surface.
REN Shuai, SUN Kang-ning, LIU Ke, PANG Lai-xue. Preparation of Ti3Al/TiC+ZrO2 Composites by Hot-press Sintering[J]. Journal of Materials Engineering, 2007, 0(1): 34-36.
Ti3Al/TiC+ZrO2 composites were prepared by mechanical alloying and hot-press sintering. The effects of different sintering temperatures (1500, 1550℃) and addition modes of Ti3Al to TiC matrix on the mechanical properties and microstructure were studied, and the fracture surfaces were analyzed with SEM. The results show that the composites have excellent properties with cooperating effects of Ti3Al and ZrO2. Intergranular cracking, transgranular cracking and some intragranular grains are all presented on the fracture morphology.
GONG Xiao-zhong, TANG Jiao-ning, LI Jun-qin, ZHOU Li, ZHANG Yu, XIN Ya-fei. Electrodeposition of Single Rare Earth Metal Gd Film in Nonaqueous System[J]. Journal of Materials Engineering, 2007, 0(1): 37-41,46.
The rare earth metal Gd film on Cu substrate was fabricated by electrodeposition in urea-NaBr-KBr-formamide solution under isolation of oxygen. The effects of the concentration of GdCl3 and the current density and electrodeposition time and pH on the morphology and Gd content of the deposited film were investigated. The results obtained by XRD,SEM,EDS and XPS show that the deposited film contains metal Gd mainly(93.56%,mass fraction) and a few oxygen. The film is dense, homogenous and smooth with silvery white colour. Too low or too high current density leads to dark grey, porous and rough deposited film. The Gd content in the film increases and then decreases as the current density increases. A polyvinyl alcohol film was deposited on the Gd film for protection of oxidation.
SUN Jun-long, DENG Jian-xin, LIU Chang-xia. Microstructure and Mechanical Properties of B4C/TiC/Mo Ceramic Composites[J]. Journal of Materials Engineering, 2007, 0(1): 42-46.
B4C/TiC/Mo ceramic composites were fabricated by hot pressing with TiC and Mo as toughening phases. The influence of preparing parameters and the content of TiC on microstructure and mechanical properties of the composites was analyzed. The bending strength, toughness, hardness and relative density of the composite prepared by the optimized process of 1900℃ under 35MPa for 45min were 705MPa, 3.82MPa·m1/2, 20.6GPa, 98.2%, respectively. B4C/TiC/Mo ceramic composites were toughened and strengthened by the combination of Mo and TiB2 formed by the reaction between TiC and B4C, which was attributed to mechanical properties of the composite.
REN Ding-gao, XIAN Cai-jun, YU Hong-ying, SUN Dong-bai, XING Ying, MENG Hui-min. Preparation of Pearly Pigment of Mica Titanium[J]. Journal of Materials Engineering, 2007, 0(1): 47-51.
The pearly pigment of mica titanium was prepared by using the liquid deposition method with the urea as precipitant. The composition and surface chemical characters of the pearly pigment of mica titanium were analyzed using XRD and SEM. The effect of the pH, reaction temperature, concentration of titanium salt, the joining speed, the joining amount of the urea, the stirring speed, crystal type promoting reagent, the calcining temperature and other parameters in the preparing procedure on the quality of pearly pigment of mica titanium was systemically studied. The technological parameters of industrial preparation for the pearly pigment of mica titanium were determined. A new preparation method was summarized which joined urea in batches and titanium salt which partly transformed from TiCl4 into TiOSO4.
WANG Xiu-fei, HUANG Qi-zhong, NING Ke-yan, YIN Cai-liu, SU Zhe-an, ZHU Jian-jun. Effects of Siliconizing on Graphitization Degree of Carbon Fiber[J]. Journal of Materials Engineering, 2007, 0(1): 52-55.
The carbon fiber was siliconized in vacuum oven at 2100℃. The surface morphology of carbon fiber was investigated by scanning electron microscopy (SEM). The composition of carbon fiber was analyzed by energy dispersive spectrum (EDS) technique. Graphitization of carbon fiber after heat-treatment and siliconizing was studied by X-ray diffraction (XRD). The results indicate that the surface and the interior of carbon fiber are composed of SiC surface with rich C element and carbon core with SiC, respectively. The spheroid SiC particles formed on the surface of carbon fiber. The SiC content in the carbon fiber is radial and grades distributing with its central content is 2.46%(mass fraction) in the fiber, gradually added to 7.53% near the fiber surface and 13.25% on the surface. The spherical particles on the fiber surface are SiC particles with rich C element, and its content is 30.55%. The graphitization degree of carbon fiber is nearly zero after heat-treatment at 2100℃,however it is about 48.5% after siliconizing at 2100℃.
ZHANG Tong-hua, YANG Bi-ling, PENG Yong-chao, YAN Xiong. Analysis on Damage Mechanism of PE/PE Self-reinforced Composite Based on Acoustic Emission Technique[J]. Journal of Materials Engineering, 2007, 0(1): 56-59,64.
Damage and fracture behavior of self-reinforced polyethylene (PE) composite under monotonic tensile loading were investigated by acoustic emission (AE) technique. AE signals released from different lay-ups composite specimens were acquired by a wideband transducer, and fracture surfaces of the specimens were observed by scanning electron microscope (SEM). Experimental results showed that the composites exhibited multiple damage modes and the characteristics of AE signals were remarkably affected by damage mechanism. AE technique is applicable in acquiring the damage information of thermoplastic composites effectively.
CHEN Hui-qin, LIN Hao-zhuan, GUO Ling, CAO Chun-xiao. Progress on Hot Deformation Mechanisms and Microstructure Evolution of Titanium Alloys[J]. Journal of Materials Engineering, 2007, 0(1): 60-64.
Research findings of the hot deformation mechanisms and microstructure evolution of titanium alloys abroad and at home currently are summarized. Characteristics of hot deformation curves, stress exponents and apparent activation energy parameters for α, α+β and β titanium alloys deforming in β, α or α+β fields, deformation patterns and recrystallization and recovery of α and β phases, globularization of α and β lamellar structure were discussed mainly.
