Effect of Fe content on glass-forming ability and crystallization behavior of a (Ti69.7Nb23.7Zr4.9Ta1.7)100−xFex alloy synthesized by mechanical alloying

(Ti69.7Nb23.7Zr4.9Ta1.7)100−xFex (x = 0, 2, 6, and 10) nanocrystalline, nanocomposite and metallic glass powders were synthesized by mechanical alloying. The glass-forming ability (GFA) and crystallization behavior of the synthesized alloy powders are investigated by X-ray diffraction, transmission electron microscopy, and differential scanning calorimetry. With the increased Fe content, the synthesized alloy powders after the steady state milling transform from full nanocrystalline structure for x = 0 to nanocomposite structure containing amorphous matrix surrounding nanocrystals for x = 2 and 6 and to full amorphous structure for x = 10, and thus has the increased enthalpy of crystallization and the increased GFA. The non-isothermal crystallization kinetics is analyzed by the modified Johnson–Mehl–Avrami (JMA) equation. The values of the Avrami exponent imply that the crystallization of (Ti69.7Nb23.7Zr4.9Ta1.7)100−xFex nanocomposite/metallic glass powders with x = 6 and 10 is governed by diffusion-controlled three and two-dimensional growth, respectively. Moreover, the crystallized bulk alloys consolidated from the synthesized alloy powders have different crystallized phases, microstructures and mechanical properties. The increased GFA with the increased Fe content could be explained by the total number of intermetallics present in the milled powders, appropriate atomic-size mismatch and large negative heat of mixing among constituent elements.

The different mechanical properties for the consolidated and crystallized (Ti69.7Nb23.7Zr4.9Ta1.7)100−xFex (x = 0, 2, 6, and 10) alloys are attributed to the different crystallized phases and microstructures induced by the different nuclei growth mechanisms of as-milled nanocrystalline/amorphous alloy powders.Figure optionsDownload as PowerPoint slideHighlights
► With the increased Fe content, the GFA of as-milled TiNbZrTaFe alloy increases gradually.
► The crystallization mechanism of as-milled alloy powders is different.
► Fe alloying addition affect the mechanical property of the crystallized alloys.
► The results provide a way for fabricating biomedical material by powder metallurgy.