Density of Ni-Al Alloys in Liquid and Solid-Liquid Coexistence State Measured by a Modified Pycnometric Method

The density of Ni-AI alloys in both liquid state and solid-liquid coexistence state was measured with a modified pycnometric method. It was found that the density of Ni-AI alloys decreases with increasing temperature and Al concentration in the alloys. The molar volume of liquid Ni-AI binary alloys increases with the increase of temperature and Al concentration. The partial molar volume of Al in Ni-AI binary alloy was calculated approximately. The molar volume of liquid Ni-AI alloy determined in the present work shows a negative deviation from the ideal linear molar volume.

Density and Structure Analysis of Molten Ni-W Alloys

Density of molten Ni and Ni-W alloys was measured in the temperature range of 1773-1873 K with a sessile drop method. The density of molten Ni and Ni-W alloys trends to decrease with increasing temperature. The density and molar volume of the alloys trend to increase with increasing W concentration in the alloys. The calculation result shows an ideal mixing of Ni-W alloys.

A Generalized Yield Criterion

A generalized yield criterion is proposed based on the metai plastic deformation mechanics and the fundamental formula in theory of plasticity. Using the generalized yield criterion, the reason is explained that Mises yield criterion and Tresca yield criterion do not completely match with experimental data. It has been shown that the yield criteria of ductile metals depend not only on the quadratic invariant of the deviatoric stress tensor J2, but also on the cubic invariant of the deviatoric stress tensor J3 and the ratio of the yield stress in pure shear to the yield stress in uniaxial tension κ/σs. The reason that Mises yield criterion and Tresca yield criterion are not in good agreement with the experimental data is that the effect of J3 and κ/σs is neglected.

Modeling of damage in materials during hot deformation based on the Zener-Hollomon parameter

By introducing the Zener-Hollomon parameter, which synthetically considersthe influence of deformation temperature and strain rate into damage mechanics, a damage evolutionmodel was developed to simulate the damage evolution of metallic materials during hot deformation.The errors between the prediction damage values and the experimental ones are within 6%.

Surface Tension of Molten Ni and Ni-Co Alloys

Surface tension of molten Ni and Ni-Co (5 and 10 mass fraction) alloys was measured at the temperature range of 1773-1873 K using an improved sessile drop method with an alumina substrate in an Ar+3%H2 atmosphere. The error of the data obtained was analyzed. The surface tension of molten Ni and Ni-Co (5 and 10 mass fraction) alloys decreases with increasing temperature. The influence of Co on the surface tension of Ni-Co alloys is little in the studied Co concentration range.

A Research into the Argument Organization in Oral English Lessons

I have designed a questionnaire to collect data and understand the actuality of argument in spoken English lessons.And I will take these data as the supporting materials in the whole article.

Study on Cracking Tendency and Mechanism of Gray Cast Iron Laser Cladding

In this paper, NiCrSiB and CoWC35 powder has been used in laser cladding of gray cast iron. The cracking tendency has also been discussed. The cracks have been observed with a scan electron microscopy to analyze the cracking mechanism. The results show that cracks have not appeared in NiCrSiB cladding. Nevertheless, the cracking tendency of CoWC35 cladding is extremely high and there are both cold cracks and hot cracks in the cladding. The cracking tendency of laser cladding depends on physical properties of the cladding material and plasticity and roughness of the cladding.

Wettability of Molten Steel/Na2O-Li2O-SiO2-B2O3 Slag System

The vacuum treatment for simultaneous desulphurization and dephosphorization of hot metal and molten steel with pre melted CaO based slag was carried out. For pre treatment of hot metal, both desulphurization and dephosphorization are improved with the increase of CaO in slag, but deteriorated with the increase of CaF 2 in slag. The average desulphurization and dephosphorization rate is 68 83 % and 78 46 %, respectively. For molten steel, the substitution of BaO for CaO in slag has minor effect on simultaneous desulphurization and dephosphorization. The desulphurization and dephosphorization rate is higher than 90 % and 50 % respectively with the lowest final sulfur and phosphorus mass percent being 0 001 2 % and 0 010 %, respectively. The overall effect of simultaneous desulphurization and dephosphorization of molten steel is better than that of hot metal.

THE CHARACTERISTICS OF HYPERSPHERES IN MINKOWSKI SPACE

Y-Riemannian metric gY is an important tool in Finsler geometry, where Y is a smooth non-zero vector field on Finsler manifold. If Y is a geodesic field, it is very effective to study flag curvature using Y-Riemann metric. In this paper, using a special Y-Riemann metric ( that is, so called v-Riemann metric ), we study hyperspheres in a Minkowski space and give some characteristics of hyperspheres in a Minkowski space.

FORMING AND PRECISION MACHINING TO NANOMATERIALS LUMP

The technology of forming and machining lump nano-materials has beeninvestigated. Grinding, abrasive machining test has been conducted to Fe, Co, Ni and Al lumpnano-materials. Experiments have been done to measure grinding force, grinding thermal, machiningroughness and micro-hardness. Image analysis is carried out by metallographic and scanning tunnelmicroscopic microscope. Researches provide the basis data for forming and machining lumpnano-materials.

STUDY ON JOINING PROCESS FOR LAMINATED OBJECT MANUFACTURING USING METALAS MODELING MATERIALS

In order to solve some key problems associated with the rapid manufacturingof metallic functional part, a new technique using vacuum solid-state pressure diffusion weldingprocess to join the metallic slice sheets is put forward. The following results can be drawn fromthe experiments: only 1 percent shrinkage happened in the stack direction and it came from theregular system error. The atoms diffuse between joint interfaces clearly and new grains formedmeanwhile. The average shear strength of welding zone is more than 100 MPa and micro hardness ofwelding zone is almost the same as that of matrix. It is shown from above results that the vacuumsolid-state pressure diffusion welding process is an available technique to join metal slice sheetsfor the rapid manufacturing of metallic functional parts.

MAKING USE OF FOREIGN TEACHERS TO HELP US IN OUR ENGLISH EDUCATION-IDEAS ABOUT THE STANDARDIZATION OF MANAGEMENT TO FOREIGN TEACHERS

In accordance with the new situation, new challenges and new opportunities that China's entry into WTO has brought about to China's education, the author analyses the advantages and disadvantages of foreign teachers' joining into our English education, pointing out that the standardization of management to foreign teachers is one of the most effective measures to tap their potentials and push forward China's English education.