Production of Zr55Cu30Ni5Al10 Glassy Alloy Rod of 30 mm in Diameter by a Cap-Cast Technique
used for the preparation of the master alloy. The purity of these metals; Zr(+Hf), Cu, Ni and Al were 99.99 mass%, 99.999 mass%, 99.99 mass% and 99.999 mass%, respectively. The alloy ingots were completely remelted, and cast into cylindrical rod samples with diameters from � 16 mm to � 30 mm by a modified cap-casting method, as shown in Fig. 1. The cap-cast technique was designed to obtain high cooling rate even at the upper part of cast specimen. The cast structure was examined by scanning electron microscopy (SEM), and the compositions of the quenched samples were determined with an electron probe microanalyzer (EPMA). The phase identification of the cast samples was performed by X-ray diffractometry. Oxygen concentration of the bulk glassy alloys was measured by a helium carrier fusioninfrared absorption. Microscopic cast structures were examined by transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM) using a JEOL 4000 FX. TEM samples were prepared by an electrolytic polishing machine using nitric methanol (30 vol% HNO3) at about 250 K.
Structure, Thermal Stability and Mechanical Properties of Zr65Al7.5Ni10Cu17.5 Glassy Alloy Rod with a Diameter of 16 mm Produced by Tilt Casting
Bulk glassy alloy rods with a diameter of 16 mm and a length of 40 to 45 mm were produced for Zr65Al7:5Ni10Cu17:5 alloy by a tilt casting method. The alloy specimens taken from the different sites which are away by about 10 mm, 15 mm and 30 mm from the bottom surface of the cast rod consist of a glassy phase and their thermal stability, mechanical properties and fracture mode are almost independent of the specimen sites. The glass transition temperature, temperature interval of supercooled liquid region before crystallization and heat of crystallization are about 643 K, 102 K and 55 J/g, respectively, for the specimens taken from the three different sites. Besides, Young’s modulus, yield strength, fracture strength, yield strain and plastic strain of the specimens are about 87 GPa, 1540 MPa, 1580 MPa, 0.018 and 0.005, respectively. The fracture mode consisting of shear plastic deformation along the maximum shear stress plane, followed by an instantaneous final rupture is also independent of the specimen sites. These data indicate that the cast glassy alloy rod with a diameter of 16 mm has nearly the same characteristics, though the cooling rate is significantly dependent on sample sites. The knowledge of producing the Zr-based bulk glassy alloy rod with nearly the same characteristics in the large diameter range up to 16 mm is encouraging for future applications of bulk glassy alloys as a new type of engineering material. [doi:10.2320/matertrans.MER2008127]
CMEOC—An expert system in the coal mining industry
Abstract This paper introduces an expert system in the mining industry, called the Coal Mining Expert and Optimization Consultation System (CMEOC). The paper mainly describes the architecture of this system, including the knowledge base, inference engine, and relevant optimization techniques. The techniques include multi-objective programming, fuzzy sets, and integer programming. The application results present evidence of the usefulness of the system.