Effect of Li Addition on Synthesis of Mg-Ti BCC Alloys by means of Ball Milling

Abstract

The effect of Li addition to Mg on synthesis of Mg-Ti BCC alloys by means of ball milling was studied. Mg-x at%Li (x ¼ 4; 20; 46) alloys prepared by the induction melting method consisted of the HCP phase (Mg-type), the HCP phase + the BCC phase (Li-type) and the BCC phase, respectively. Lattice parameters of the HCP phase decreased with the increase in x, whereas those of the BCC phase at x ¼ 20 and 46 were smaller than that of Li. Mg-x at%Li (x ¼ 4; 20; 46) alloys and Ti were milled for 50-200 h in an argon atmosphere. Formation of Mg 96 Li 4 Ti 100 BCC alloy was confirmed by X-ray diffraction (XRD) measurements after 50 h milling. By Li addition to Mg, the synthesis time of the BCC phase was shortened. Li made Mg deformation facile by the activation of the non-basal slips in Mg, and raw materials were efficiently milled. The crystallite size of Ti was readily reduced and formation of the BCC phase was accelerated. The crystallite size and lattice parameter of Mg 96 Li 4 Ti 100 BCC alloy were similar to those of Mg 100 Ti 100 BCC alloy.

Formation of metastable phases in magnesium–titanium system by high-pressure torsion and their hydrogen storage performance

“…Borsa et al reported that a Mg-Ti alloy with the hcp structure is formed by co-sputtering of Mg and Ti in Ar atmosphere [18]. Asano et al [19][20][21], Rousselot et al [22], Calmak et al [23] and Maveja et al [24] reported that several metastable phases with bcc, fcc and hcp structures are formed in the Mg-Ti system by application of high-energy ball milling to Mg and Ti powders in Ar atmosphere.…”

Nanocrystalline Metal Hydrides Obtained by Severe Plastic Deformations

“…In the case of magnesium, the deformation is mainly by basal plane slip (0001)< −12-10> while for titanium twinning deformation is more important [65]. In one investigation, Asano et al had the idea of adding lithium to magnesium in order to reduce the yield stress of magnesium and also to decreases its lattice parameter [65]. They found that by adding Li to Mg the deformation of Mg was easier and the Ti crystallite size was reduced.…”

“…Although both Mg and Ti have a hexagonal closed packed (HCP) structure, during milling of a Mg and Ti mixture they react differently. In the case of magnesium, the deformation is mainly by basal plane slip (0001)< −12-10> while for titanium twinning deformation is more important [65]. In one investigation, Asano et al had the idea of adding lithium to magnesium in order to reduce the yield stress of magnesium and also to decreases its lattice parameter [65].…”

“…The synthesis of Mg-Ti BCC alloys by mechanical alloying has been extensively studied by Asano et al [48,49,57,65,66]. Although both Mg and Ti have a hexagonal closed packed (HCP) structure, during milling of a Mg and Ti mixture they react differently.…”

“…However, these techniques could not be scaled-up to industrial level and other methods have to be investigated. Mechanical alloying has demonstrated its high efficiency for producing metastable Mg-Ti alloys starting from elemental Mg and Ti powders [48,56,[63][64][65][66].…”