Carbide-binder interface ledges in (V,Ti) C+ (Ni,Mo) cermets

Interface ledges have been observed by transmission electron microscopy between the carbide and binder phases in (V, Ti) C+ (Ni, Mo) cemented carbides. It is proposed that these ledges can act as dislocation sources in a manner analogous to that of polycrys-talline metals and alloys. Such a concept can provide a physical basis for the empirically observed relation between hardness and the binder mean free path in cemented carbides. R. K. VISWANADHAM, formerly with Martin Marietta Laboratories, 1450 S. Rolling Road, Baltimore, MD 21227     

从低品位铜钼矿体中回收铜钼的浮选试验研究

文章通过对福建、内蒙古、河南某地三个低品位铜钼金属矿体的铜钼浮选试验研究,讨论了低品位铜钼金属矿体的铜钼浮选可选性。？昆合浮选较优先浮选指标好,从含Cu0．03％～O．44％,含MoO．039％～0．081％的给矿中得到含Mo34．82％～47．46％,含cu4．65％～18．42％,回收率分别为62．50％～81．47％和58．89％-82．03％的钼精矿和铜精矿。     

Thermodynamic prediction of the ae3 temperature of steels with additions of Mn,Si, Ni,Cr, Mo,Cu

Published binary phase diagrams and activity data for iron and binary and ternary alloys have been used to evaluate the general linear series expansion of the activity coefficient and the standard free energy changes and these have been employed in turn for the accurate thermodynamic determination of the Ae₃ temperature in steels with additions of Mn, Si, Ni, Cr, Mo, and Cu. A computer program accurate for total additions up to 7.0 wt pct and an analytic formula accurate for total additions up to 2.5 wt pct have been developed. The predicted Ae₃ temperatures compare favorably with observations on over 200 steels from international compendia. It is demonstrated that existing linear regression formulae are incorrect and that for low alloy additions they should be replaced by linear expressions with carbon concentration dependent coefficients.     

Microstructure, mechanical properties, and fracture mechanism of As-cast (Ti0.5Cu0.25Ni0.15Sn0.05Zr0.05)100−x Mo x composites

Copper mold cast cylinders of (Ti_0.5Cu_0.25Ni_0.15Sn_0.05Zr_0.05)_100−x Mo _x composites are prepared. Addition of Mo in the bulk glass-forming alloy induces the formation of a dendrite/matrix composite. For 3-mm-diameter cylinders, the matrix exhibits a homogenous ultrafine microstructure for Mo content of 2.5 at. pct, and a fine eutectic microstructure for 5 at. pct Mo. For 5-mm-diameter cylinders, the matrix exhibits a dendritic microstructure for 2.5 at. pct Mo, and exhibits a coarser eutectic microstructure for 5 at. pct Mo. Despite the formation of a dendrite/nanostructured matrix composite in the cylinders, the quenched surface layer with a nanoscale grain size dominates the deformation and fracture of the 3-mm-diameter cylinders. More than 56 vol pct quenched layer leads to a distensile fracture mode and the samples exhibit high fracture strength and high Young’s modulus but low ductility. For 5-mm-diameter cylinders, the composite microstructure becomes dominant due to its more than 64 vol pct volume fraction leading to a cone-shaped fracture surface. The samples exhibit lower yield strength and lower Young’s modulus but better ductility compared to the 3-mm-diameter cylinders. The mechanical behavior of the Mo-bearing composites strongly depends on the microstructural homogeneity and casting defects formed upon solidification.     

Structure formation in binary Al-TM (TM = Mn,Co, Ni,Cu) melts

The structures of binary Al-TM (transition metal TM = Mn, Co, Ni, Cu) melts at near-liquidus temperatures are studied by X-ray diffraction and simulation using the reverse Monte Carlo method. The melts are found to have chemical local atomic ordering, and this ordering depends on the nature and content of TM. Chemical local atomic ordering leads to a medium-range order as a result of TM atom localization at distances of 0.4–0.5 nm in the composition of polytetrahedral clusters having icosahedral symmetry. A medium-range order in the melts is identified due to the presence of an additional maximum (prepeak) in the left slope of the first peak in experimental structure factor curves. The local atomic orders in the melts and the corresponding crystalline and quasicrystalline phases are found to correlate with each other.     

Cu（II）、Ni（II）离子在蛇纹石表面的吸附及对其浮选的影响

通过吸附量测试、纯矿物浮选和红外光谱分析,研究Cu2+和Ni2+离子在蛇纹石表面的吸附过程及对蛇纹石浮选的活化机理.Cu2+和Ni2+离子在蛇纹石表面的吸附符合二级动力学模型,等温吸附过程符合Langmuir等温吸附模型,吸附能够自发进行,为物理吸附和化学吸附的共同作用,Cu2+和Ni2+离子在蛇纹石表面的吸附量随p H值升高而增大.Cu2+和Ni2+离子在弱碱性条件下对蛇纹石具有活化作用,活化机理为铜镍的氢氧化物沉淀和羟基络合物作用于蛇纹石表面,形成活性位点,黄药在活性位点上吸附生成黄原酸铜或黄原酸镍,从而使蛇纹石表面疏水性增大,浮选受到活化.      

Electrochemical Behavior of Bulk Amorphous Steel Fe55M2Cr12Mo10B5C13Y2(M=Ni,Cu,Nb)

Fe55Ni2Cr12Mo10B6C13Y2,Fe55Cu2Cr12Mo10B6C13Y2 and Fe55Nb2Cr12Mo10B6C13Y2 alloys with diameter of 4 mm were produced by copper mold casting. The effect of alloying additions (Ni,Cu or Nb) on corrosion resistance of Fe55 Ni2 Cr2Mo10 B6 C13 Y2,Fe55Ni2Cr12Mo10B6C13Y2 and Fe55 Cu2 Cr12 Mo10 B6 C13 Y2 alloys was studied by polarization curves and electrochemical impedance spectroscopy (EIS). The results show that Fe55Ni2Cr12Mo10B6C13 Y2 and Fe55Cu2Cr12Mo10B6C13 Y2 alloys can be cast to form bulk metallic glasses. Fe55Ni2Cr12Mo10B6C13 Y2 and Fe55Cu2Cr12 Mo10B6C13Y2 amorphous alloys with passive potential about 1500 mV exhibit good corrosion resistance in NaCl solution of 5 % and 1 mol/L HC1 solution. The passive current density of the alloy with Ni addition is lower than that of other alloys. EIS results only show one impedance element. Amorphous alloy Fe55 Ni2 Cr12 Mo10 B6 C13 Y2 with larger charge transfer reaction resistance indicates good corrosion resistance.     

Electrochemical Behavior of Bulk Amorphous Steel Fe55M2Cr12Mo10B6C13Y2（M=Ni, Cu, Nb）

 Fe55Ni2Cr12Mo10B6C13Y2,Fe55Cu2Cr12Mo10B6C13Y2 and Fe55Nb2Cr12Mo10B6C13Y2 alloys with diameter of 4mm were produced by copper mold casting. The role of alloying additions (Ni, Cu or Nb) on corrosion resistance of Fe55Nb2Cr12Mo10B6C13Y2, Fe55Ni2Cr12Mo10B6C13Y2 and Fe55Cu2Cr12Mo10B6C13Y2 alloys were studied by polarization curves and electrochemical impedance spectroscopy (EIS). The results show that Fe55Ni2Cr12Mo10B6C13Y2 and Fe55Cu2Cr12Mo10B6C13Y2 alloys can be cast into bulk metallic glasses. Fe55Ni2Cr12Mo10B6C13Y2 and     

The effect of V/Ti ratio on the partitioning of mo in (V,Ti) + (Ni,Mo) cemented carbides

The performance of a series of (V,Ti)C + (Ni,Mo) cermet systems with a given Mo content and varying V/Ti ratios in the carbide has been evaluated through hardnessvs crack resistance plots. It is shown that the partitioning of Mo between the binder and the carbide in these cermets is sensitive to the V/Ti ratio of the carbide. For both low and high V/Ti ratios, most of the Mo is in the carbide phase, but through different mechanisms. For intermediate V/Ti ratios, most of the Mo is in solid solution in the binder and provides strengthening. The best overall system performance is achieved when this ratio is close to unity, as borne out by the crack resistancevs hardness comparisons.     

Mg-TM(TM=Cu,Ni,Zn)-Y体系长周期有序(LPO)相的研究

In this work, a systemic study has been performed to the Mg-TM(TM=Cu, Ni, Zn)-Y alloys. It has been proved that a long period ordered (LPO) phase is stable in all these systems with limited solubility ranges of Cu, Ni, Zn and Y. The equilibrium composition of the LPO phase has been determined accurately, and the phase relationships concerning the LPO phase have been established. Based on this, ideal n(TM)/n(Y) ratios for getting the LPO phase have been obtained, which are important for the composition design of the LPO Mg-based alloys.     

Effects of different alloying elements M (M =Fe,Ni,Mn,Si,Mo,Cu,Y)on Cr2O3 with Cl:a first-principles study

Using the first-principles methods,the effects of different alloying elements M (M =Fe,Ni,Mn,Si,Mo,Cu,Y) on Cr2O3 with C1 adsorption are studied.The results sho...     

ICP-AES法测定不锈钢中高含量Mn、Cr、Ni、Cu、Mo的不确定度评定

对电感耦合等离子体发射光谱(ICP-AES)法测定不锈钢中高含量的Mn、Cr、Ni、Cu、Mo的不确定度进行了评定,建立了相应的数学模型,对数学模型中各个参数进行了不确定度来源分析,并在此基础上计算各不确定度分量、合成标准不确定度和扩展不确定度,为系统分析检测结果的准确程度和方法的可靠性研究提供参考.