Formation of Non-Solid Soluble Type Cu-Based Amorphous Alloy and Its High Functional Properties by Nanocrystallization

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Cu-Ag-Ln alloy system which includes above 90at% of non-solid soluble elements was amorphized. The amorphous structure, the structural change after nanocrystallized and the thermal stabiliy of ternary amorphous alloys were studied. The amorphous structure was obtained in the concentration range at 20-70 at% of Ag and 3-10 at% La in the Cu-Ag-La system, and 30-55 at% of Ag and 3-8 at% of Ce in the Cu-Ag-Ce system.It was shown in these amorphous alloys that the high crystallization temperature as 400-500K and high values of Vickers hardness, tensile strength and Young's modulus as 300,750Mpa and 120Gpa, respectively.Especially, in spite of Cu-based alloys, specific electrical resistivity is high as 0.75-0.90 mu・OMEGA・m, and the strain gauge factor was high as 2.4, reflecting higher sensitivity for stress. The crystallization process was examined by means of X-ray or electron diffraction and transmission electron microscope.In the first stage, following reaction,Am * Am + fcc Cu(Ag) + fcc Ag(Cu)* Cu + Ag + unknown Compondwas observed, and the nano order scale fine crystallite of fcc phase precipitates primarily, accompanying betterment of mechanical property as maximum value of tensile strength of 950Mpa. The activation energy obtained from the rate of the crystal growth was estimated as 130-160kJ/mol. Furthermore, by analyzing of these physical property, the imporovement of more excellent characteristics will be designed from the view point of alloy composition or heat treatment, and be tested the possibility of application to the sensor or actuator materials.As it was confirmed in the preexamination that Cu based amorphous alloys showed the peculiar property for oxidation behavior, the investigation of this field will also be spread.