The enhancement of the thermal stability of the amorphous structure in Al-Ca-Ni alloy has been investigated in two steps: 1) selection of ternary Al-Ca-Ni composition; and 2) effect of addition of Y. The thermal stability of the amorphous structure is significantly improved by the addition of Y in Al87.5Ca7.5Ni5 alloy. Among the alloys investigated in the present study, i.e. (Al87.5Ca7.5Ni5)100-xYx (x = 0, 1, 2, 3 and 4 at%), alloys with ≥2 at% Y exhibit glass transition behavior during heating and viscosity drop at the supercooled liquid region. The activation energy for the first-step crystallization increases with increasing Y amount, i.e. from 167 kJ/mol for Y = 0 at% alloy to 347 kJ/mol for Y = 4 at% alloy, indicating that the thermal stability of the amorphous structure is improved with Y addition. The increase of activation energy for crystallization may be due to the change of crystallization mode depending on Y amount; eutectic crystallization (Y = 0 at%) → polymorphic crystallization (Y = 2 at%) → primary crystallization (Y = 4 at%).
Bibliographical noteFunding Information:
This research was supported by Basic Science Research Program through the National Research Foundation by the Ministry of Science, ICT and future Planning ( 2016R1A2B2013838 ). W.T. Kim acknowledges the support from Cheongju University through 2017 sabbatical leave program.
© 2018 Elsevier B.V.
All Science Journal Classification (ASJC) codes
- Mechanics of Materials
- Mechanical Engineering
- Metals and Alloys
- Materials Chemistry