Effects of rare earth Ce addition on microstructure and mechanical properties of impure copper containing Pb

The effects of rare earth Ce on the microstructure and mechanical properties of impure copper containing Pb were investigated using OM,SEM,EPMA,TEM and tensile testing.TEM and EDS analysis reveal that spherical CePb3 particles form after Ce addition.CePb3 particles,with average size of^3.6μm,homogenously distribute in the Cu matrix.Due to small lattice misfit(~4.62%)with Cu matrix,CePb3 particles can act as effective nucleation sites beneficial to the grain refinement.Pb at grain boundaries seriously deteriorates the mechanical properties of Cu.The tensile strength and the elongation of Cu-0.1 Pb are decreased by 43.1%and 56.7%compared with those of pure copper,respectively.Ce can purify grain boundaries,cause the precipitation of CePb3 particles and refine grain sizes,which contribute to significant improvement of the mechanical properties of Cu.Compared with Cu-0.1Pb,the tensile strength(179 MPa)and the elongation(38.5%)of Cu-0.1Pb-0.3Ce are increased by 117.6%and 151.6%,respectively.

Microstructure and properties of TP2 copper tube with La microalloying by horizontal continuous casting

The TP2 copper tube was prepared with La microalloying by horizontal continuous casting(HCC). The absorptivity of La and its effects on microstructure, tensile and corrosion properties of HCC TP2 copper tube were studied by means of the inductively coupled plasma optical emission spectrometer(ICP-OES), optical microscope(OM), scanning electron microscope(SEM) and potentiodynamic polarization measurements. The results show that the absorptivity of La in the HCC TP2 copper tube is about 15% under antivacuum conditions due to the good chemical activities of La. The impurity elements in copper tube such as O, S, Pb and Si can be significantly reduced, and the average columnar dendrite spacing of the copper tube can also be reduced from 2.21 mm to 0.93 mm by adding La. The ultimate tensile strength and the elongation with and without La addition are almost unchanged. However, the annual corrosion rate of the HCC TP2 copper tube is reduced from 10.18 mm·a^(-1) to 9.37 mm·a^(-1) by the purification effect of trace La.

High-temperature modification and air-quenching granulation of steel slag

To solve the problem of difficult utilization of steel slag,the liquid steel slag was modified and the air-quenching granulation process was carried out to make steel slag into a value-added end product:air-quenching granulated steel slag.The granulated slag was tested to analyze the variation rule of slag properties under different modification conditions.Based on the phase diagram of CaO–Si_(2)O–FeO–MgO–Al2O3 slag system,the feasibility of blast furnace(BF)slag as modifier was determined.When the addition of BF slag was increased from 0%to 35%,following results were obtained.The slag fluidity was improved,and the air-quenching temperature range was expanded.Then,the yield of air-quenched steel slag increased,while the granulation rate,the degree of sphericity,the compactness were decreased.Furthermore,the air-quenching granulation process could substantially improve the stability and the amorphous content of steel slag.The maximum removal rate of free CaO was above 80%and the amorphous content was up to 95%.Taking the factors of yield and properties of granulated steel slag into full consideration,the optimum proportion of BF slag is around 15%.

Structure characterization and grinding performance of gas-quenched steel slag abrasive

Gas-quenched steel slag abrasive was obtained by gas quenching with high-temperature liquid steel slag as raw material.The phase composition,thermal properties,micromorphology,magnetic properties,and mechanical properties of the par-ticles were characterized by using an X-ray diffractometer,a differential thermal analyzer,a scanning electron microscope,a magnetic property meter,and a compressive strength tester,respectively.Results show that the gas-quenched steel slag abrasive is a monodisperse regular sphere.The compressive strength of a single particle is 34 N.The product is ferromag-netic and has good thermal properties.The micromorphology and flatness of the workpiece before and after grinding with the gas-quenched steel slag abrasive were measured using a three-dimensional profilometer.Results reveal that the surface roughness of the workpiece is reduced to 1.526,0.623,and 0.227μm after grinding for 5,10,and 20 min,respectively.The surface profile fluctuation decreases to±1.0μm.Thus,the workpiece surface tends to be flat without obvious scratches.