Advanced Materials Research Vols. 750-752

Abstract: The effect of Fe on the performance of rare earth aluminum conductor was investigated in this paper. The tensile strength, elongation and conductivity of the alloys were tested. The study results showed that Fe can significantly increase the tensile strength and elongation of the aluminum rod. However, with the increasing content of Fe, the conductivity of the aluminum rod reduced more obviously. In comprehensively considering the tensile strength, elongation and conductivity, the alloy gained better mechanical properties and conductivity when ω (Fe) was 0.3%.

Abstract: The strengthening mechanism, properties and applications of magnesium alloy with resistance to high temperature and creep resistant were introduced. The effects of some kinds of elements in magnesium alloy and the preparation methods were also elaborated. At last, the development trend of magnesium alloy was overviewed.

Abstract: The damage and fracture behavior was researched in hot compression of as-cast Ti40 titanium alloy with single β phase. The main fracture modes consist of 45° shear fracture, inner cracking and longitudinal fracture on free-surface, which occur at 850°C/10s^-1, 900~950°C/10s^-1 and other deformation conditions respectively. Moreover, 45° transgranular cracking is the combination result of adiabatic shear bands due to local temperature rise and shear stress, the inner intergranular cracking is induced by the microvoids near the adiabatic shear bands propagted along grain boundry under shear stress, the surface longitudinal intergranular cracking is caused by the vaporization of oxide and function of hoop tensile stress. In addition, the material undergoes the complex fracture which has to be avoided or decreased in hot processing for obtaining satisfactory properties.

Abstract: Hot compression testing of as-cast Ti60 alloy was carried out 970-1120 °C, 0.01-10 s¹ and 30-75%. The fracture behavior of the alloy was investigated by light optical microscope, scanning electron microscope. The result shows that, at high strain rate and large height reduction, 45° transgranular fracture and longitudinal intergranular fracture are observed, which are confirmed to be transgranular cleavage brittle fracture and ductile fracture respectively. Moreover, the cracking degree increases with the increasing height reduction. Besides, the alloy deformed at high temperature exhibits a good ductility, whereas lots of longitudinal cracks occurs on its surface due to the brittle alpha-case formation. Consequently, the systematic analysis on the fracture mechanism for as-cast Ti60 alloy is vitally necessary for the optimization of processing parameters in its cogging process.

Abstract: Ni-Mn-In is a new type of magnetic shape memory alloy, but in the stoichiometric Ni₂MnIn, the martensitic transformation cannot perform. Thus, in order to obtain the appropriate Curie temperature T_C and the martensitic transformation temperature T_M, the composition adjustment must be carried out around the stoichiometric Ni₂MnIn. The process of composition adjustment would induce various point defects. This paper scientifically studies the magnetic properties of off-stoichiometric Ni₂MnIn alloys by first-principles calculations.

Abstract: Effects of the technological parameters (superheat, cycle times and holding time) on undercooling and structure of Ag-28.1 wt.% Cu eutectic alloy were discussed by orthogonal experiment. It shows that the influence of the superheat on undercooling is biggest, followed by cycle times, and finally holding time. Then the optimum process parameters of getting different undercooling are given in this paper. In the Ag-28.1 wt.% Cu eutectic alloy melt, cellular growth of lamellar eutectics takes place because of the large difference in composition between the two eutectic phases and the very large thermal diffusion coefficient of the liquid, and when undercooling is equal to or higher than 76 K, lamellar eutectics grow in a dendritic form during rapid solidification.

Abstract: The transient liquid phase diffusion bonding (TLP-DB) was employed to join TiNi shape memory alloy (SMA) and stainless steel (SS) with an interlayer metal of Ag-Cu eutectic metal foil.The corrosion behavior of the TLP-DB joint in Hanks solution at 37°C was investigated by electrochemical methods.The results show that the corrosion resistance of the joint is comparable to, but lower than that of base metals during the early anodic polarization, and the corrosion rate of the joint is between that of TiNi SMA and SS in the transpassive region at high potentials. The corrosion resistance of the specimens in Hanks' solution is associated with the surface quality, mircotructure and the intermetallics. Both TiNi SMA and SS display the characteristics of localized corrosion with a little pitting corrosion, while the joints mainly show the characteristics of pitting corrosion concentrated on the enrichment Cu phases.

Abstract: The kinetics of the martensite decomposition in TC21 alloy under isothermal conditions has been studied using dilatometry technique. The typical morphologies of decomposition products were also directly observed. At 500°C and 550°C, the mechanism of martensite decomposition occur by, at temperature between 600°C and 750°C, the martensite decompose by . up 800°C, the martensite directly transform to α and β phase. Time–temperature–transformation diagram with iso-lines tracing the amount of the martensite decomposition have been established.

Abstract: A technology conception of producing filled metal particles which use steel scraps of steelworks as the main raw materials for welding was proposed in this paper. It provides a new resource for raw materials which are used to process welding material and the steel scraps are used sufficiently, reasonably and in high value-added at the same time. According to the wearing conditions of loader when it exploits and loads the river sand, the Fe-Cr-C alloy particles were designed. The technology of medium frequency induction furnace - centrifugal atomizer was used to get the alloy particles in 0.1~5.0mm diameter. Melt alloy particles by submerged arc welding and study the microstructure and properties of the deposited metal. Engineering application tests were also carried out and yield highly desirable results.

Abstract: Nanocrystalline Cu90Nb10 alloy was produced by high energy ball milling mechanical alloying (MA). The effects of ball milling time on the microstructure and mechanical property of this alloy in the process of MA were investigated. The results show: up to 10 at.% Nb could be dissolved into Cu matrix by MA; the powder particles became compacted and homogeneous with increasing the ball milling time, and the deformation degree also increased synchronously; the grain size of this alloy was refined gradually, and it reached the minimum value of 11.5 nm after 30h milling; the microhardness of this alloy increased with increasing the milling time, and it obtained the maximum value of 328 Hv after 30h milling. The obvious reinforcement of this alloy may be due to the comprehensive effects of the fine grain strengthening, the solid solution strengthening and the strain strengthening.