Papers by Keyword: Arc-Melting

Abstract: In this study, the W-Si-C multi-phase composites were fabricated by an arc melting method. With addition of SiC, the grain size of W is obviously reduced, and the small angle misorientation becomes dominate, which is beneficial for the improvement of deformability. The effects of SiC additions (from 0.5 to 3wt%) on the microstructure and mechanical properties are mainly investigated. With 1 wt% SiC addition, the flexural strength reaches the highest value. The self-generation of W₅Si₃ may enhance the strength and ductility, but too much W₅Si₃ exists as brittle BP (Brittle to Plastic) microstructure. The highest flexural strength is obtained at approximately 1 vol% W₅Si₃.

Abstract: High temperature phase (HTP) MnBi alloys were formed using the arc-melting method. The drastic difference in the melting points of Mn and Bi resulted in non-homogeneity. The MnBi, Mn, Bi and O were detected by energy dispersive spectrometry (EDS). The field emission scanning electron microscope (FESEM) revealed the morphology of each phase. The rod-like and flower-like nanostructures were consistent with Bi₂O₃ as indicated by EDS and X-ray diffactometry. The HTP MnBi was transformed to the low temperature phase (LTP) following the annealing process. The remaining Bi and Mn are susceptible to oxidation leading to the subsequent formation of Bi₂O₃ as well as MnO. Whereas LTP MnBi alloys are useful for their hard magnetic properties, Bi₂O₃ nanowire is receiving attention for potential applications in optoelectronic devices.

Abstract: TiB₂-TiC, TiB₂-TiN and TiB₂-TiC_xN_1-x composites were prepared by arc-melting mixtures of TiB₂, TiC and TiN powders. 28TiB₂-72TiC (mol%) composite showed a lamellar eutectic structure, while 55TiB₂-45TiN (mol%) composite with a lamellar structure consisted of TiB₂, TiN and TiB. 36TiB₂-44TiC-20TiN (mol%) was a quasi-binary eutectic composite having a rod-like structure.

Abstract: Cu-10Ni-5Mo alloys have been prepared by arc-melting and induction melting injection moulding. The effects of melting processes on the microstructure and thermal conductivity of Cu-10Ni-5Mo alloys were studied. The results show that the grain of Cu-10Ni-5Mo alloy prepared by arc-melting is coarse and the structure includes α solid solution and Mo-Ni phase. The grain of Cu-10Ni-5Mo alloy prepared by induction melting injection moulding is superfine and the structure is α solid solution. Under this experiment condition, the coefficient of thermal conductivity of Cu-10Ni-5Mo alloy prepared by arc-melting is 56.9 W/(m•K)，while that of Cu-10Ni-5Mo alloy prepared by induction melting injection moulding is 35.7 W/(m•K). The melting points of Cu-10Ni-5Mo alloy prepared by two methods all increase and are little different.

Abstract: The glass-ceramics were made of arc-melting slag from incinerator fly ash mixed with glass cullet additive by sintering method. The effects of ball milling time and powder compaction pressure on the microstructure, physical and mechanical properties of the glass–ceramics were respectively investigated. Results showed that with milling time delaying, granularity of the parent glass evidently reduces, the major phases of glass–ceramics have no change but the diffraction peaks present intensive trend, the crystal sizes of glass–ceramics decrease, the properties such as volumetric densities, compressive strength, bending strength and toughness are improved, the appropriate milling time is 6h with fifty percent of the volume (d50 value) of 10.62μm. The physical and mechanical properties first increase and then decrease with compaction pressure increasing, and the optimal compaction pressure is 60MPa.

Abstract: Arc-melting was employed to synthesize BaTi₂O₅ powders by fast melting the reagent mixture of BaCO₃ and TiO₂ with different molar ratios (0.90~1.05:2). The influence of molar ratios of BaCO₃ to TiO₂ on the phase of the powders derived from arc-melting was investigated by X-ray diffraction and Raman spectra. When the molar ratio was larger than 0.95:2, a little amount of Ba-rich compound Ba₂TiO₄ was produced besides the main phase of BaTi₂O₅. Ti-rich compound Ba₆Ti₁₇O₄₀, BaTi₂O₉ and TiO₂ began to appear at the ratios ranging from 0.90:2 to 0.95:2. Single-phased BaTi₂O₅ powders were obtained by arc-melting the reagent mixture with the molar ratio of 0.95:2.

Abstract: Hypereutectic Cu₉₈Cr₂ alloys were prepared by vacuum arc melting and electromagnetic levitationing method. The microstructure evolution was investigated during the solidification process. It is shown that for the arc melted hypereutectic Cu₉₈Cr₂ alloy, the general microstructures consist of primary β(Cr) grains distributes on α(Cu) matrix and (α+β) eutectics set in cellular α (Cu) phase. However, due to the different solidification rate, the primary β(Cr) phase, (α+β) eutectics and α(Cu) phase coexist for the electromagnetic levitated hypereutectic Cu₉₈Cr₂ alloy. The reason for the different microstructure and evolution for the hypereutectic Cu₉₈Cr₂ alloy is studied in this paper.

Abstract: Inter-metallic compound of Ti₃SiC₂ was produced via modified-SHS (self-propagating high temperature synthesis). Elemental powders of titanium, silicon and graphite were weighed according to their stoichiometric ratios (3:1:2) respectively. These powders were ball milled for 1 hour, then compacted into cylindrical shape. Synthesis of Ti₃SiC₂ was carried out by using arc melting method. The effect of different arc melting time of 10, 30 and 60 seconds was studied. Phase formation and microstructure were analyzed by using XRD and SEM. The formation of Ti₃SiC₂ was confirmed by XRD, and the SEM micrograph shows that the grain is in needle shape. XRD result also shows that the impurities are present in all the samples. TiC appeared to be the common and dominant impurity in all samples, with relatively low intensities in Ti₅Si₃ and TiSi₂ phases. Some raw materials phase was still existed in sample arc melted for 10 and 30 seconds. Hence, it can be deduced that the raw materials had not yet fully taking part in the formation of Ti₃SiC₂.

Abstract: ZrB2-SiC composites were prepared by arc melting using ZrB2 and -SiC powders as raw materials and their oxidation behavior were investigated. The eutectic composition of the ZrB2-SiC system was ZrB2-58.5mol%SiC and the melting point temperature was about 2570 K. At 1673 K mass gain was observed in the oxidation of ZrB2-SiC eutectic composition and the mass gain rate increased with decreasing Ptot. The oxide scale consisted of an amorphous SiO2 layer, a ZrO2-SiO2 eutectic-like layer and a Si-deficient layer.

Abstract: Poly- and single-crystalline BaTi2O5 co-substituted with SrO and ZrO2, Ba0.99Sr0.01(Ti1-xZrx)2O5 (BT2SZ) were prepared by arc-melting and floating-zone (FZ) melting, respectively. The specimens showed a significant (020) orientation. The highest permittivity of poly-crystalline BT2SZ was 3880 at x = 0.005 and that of single-crystal was 27000 at x = 0.005. The Curie temperature (Tc) of poly-crystals decreased from 750 to 640 K with increasing x from 0 to 0.026 and that of single-crystals decreased from 750 to 710 K with increasing x from 0 to 0.008. The highest remnant polarization of single crystalline BT2SZ was 7.8×10-2 Cm-2 at x = 0.008, higher than that of the poly-crystal.