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金属学报 2006
E/A-CONSTANT PHENOMENA IN TI-ZR-NI-CU GLASS-FORMING SYSTEM
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Abstract:
A series of alloys with e/a (i.e. valence electron per atom) value of 1.200 and Ra (average atomic size) of 0.1474 nm has been designed in Ti-Zr-Ni-Cu system based on the quasicrystals-forming composition Ti40Zr40Ni20, then the alloy rods with diameter of 3 mm were fabricated by the conventional suction casting method. The experiments showed that a bulk glass alloy can be obtained in the vicinity of Ti12Zr55Ni13Cu20, and at the compositions of Ti3Zr60Ni12Cu25 and Zr60Ni10Cu30 the another glass-related phase tI-Zr2Cu is formed. The above quasicrystal, bulk metallic glass and tI-Zr2Cu phase are a group of electronic compounds with nearly same e/a, indicating that the e/a-constant criterion is valid for Ti-Zr-Ni-Cu glass forming system. Meanwhile, the structural correlations between the icosahedron and truncated octahedron clusters (Zr2Cu) can be considered as a structural model to describe the polymorphous transformation from quacrystals or metallic glass to Zr2Cu-type phase.
