| In this paper Zr60 C u25Fe5 Al10 amorphous alloy was chosen to be the research object, and the crysta llizat ion k inet ics of Zr60 C u25 Fe5 Al10 glassy alloys were studied. In order to improve the room te mperature mechanica l properties, the Zr60 C u25Fe5 Al10 amorphous allo y was treated by isotherma l annea ling and micro-alloying. The effect of isotherma l annealing and micro- alloying on the properties of the Zr 60 C u25Fe5 Al10 amorphous al oy was investigated.Crystallizat ion kinetics of Zr60 C u25Fe5 Al10 glassy a lloys were invest igated in isotherma l and non- isother mal(cont inuous heat ing) modes. During cont inuous heat ing process, the effective activat ion energies inc lud ing Eg, Ex and Ep were calc ulated by K issinger and O zawa equat ions, Eg =383 and 403 k J/mo l, Ex=290 and 303 kJ/mo l as well as Ep =325 and 338 k J/mol. Dur ing isother ma l process, the avra mi exponent was described by the JMA equation. The avrami exponent n ranges fro m 2.64 to 3.07 when the crystallized volume fract ion is in the range from 15% to 85%, which indicated that the crystallization is controlled by a diffusio n- controlled three-dime nsiona l growth wit h increasing nucleat ion rate. Activat ion energy for crystallizat ion calc ulated by using Arrhenius equation was 385 k J/mol dur ing isother mal tra nsfor matio n process, which is larger than that during continuous heating process.The Zr60 C u25Fe5 Al10 glassy allo ys can keep its amorphous structure after 8 h annealed at 473 K. With the extens ion of the isother ma l time, the hardness of the samp le first increases and then tends to be stable. The compression tests at room temperature show that the fracture strength and plastic strain of the annea led samp les are significant ly improved. Especially, the plastic strain of the samp le annealed 4 h at 473 K increases to 4.3%. The fracture strengt h of the sample annea led 8h at 473 K increases to 1786 MPa, which improves by 14% c ompared to as-cast samp le. Wit h the extension of t he isotherma l t ime, the glass trans it ion temperature and crystallizat ion temperature of the samp les shift to lower temperature region, and crystallizat ion enthalpy of annealed samples first increases and then tends to be stable.The addit ion of Ag ele ment reduces the thermal stability of the Zr 60 C u25Fe5 Al10 bulk a morphous alloy. With the increase of the Ag content, the glass forming abilit y and the activat ion energy reduce correspondingly. respective ly.When the Ag content increases fro m 0 to 2 at.%, the supercooled region ΔTx reduces from 99 K to 92 K, while the reduced glass transit ion te mperature Trg and the parameter γ of this a lloy reduce fro m 0.555 to 0.543 and fro m 0.373 to 0.352,respective ly. The comp ressive fracture stress and the plast ic stain of the Zr-C u- Fe- Al- Ag amorphous alloy system increase w ith the Ag content increases. When the Ag content reaches to 2 at.%, the alloy has the largest plastic strain in compression of around 5.8% and fracture st rengt h up to 1644 MPa.The high dens ity of shear bands and the enhanced interactions between the shear bands lead to the superior plasticity of this bulk metallic glass. |
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