Abstract: Lithium is one of the active metals and reacts with nitrogen even at room temperature.
In this study, in order to grind and activate Li, the mechanical milling of Li with stable metal oxide,
namely, Al2O3 and MgO, using a high energy vibrating ball mill was performed. In the case of Li-
MgO system, it reacts with N2, but hardly reacts with O2. The reaction with N2 generally produces
Li3N, while for some vigorous reactions the Mg3N2 and Li2O are produced as the major phases. In
the case of Li-Al2O3 system, however, reactivities with both N2 and O2 are high. The difference will
be explained in terms of the reaction mechanism and the Li state.
Abstract: Mechanochemical synthesis of zinc ferrite, ZnFe2O4, was attempted from a powder
mixture of iron (III) oxide, alpha-Fe2O3 and zinc (II) oxide, ZnO. Nanocrystalline zinc ferrite,
ZnFe2O4 powders were successfully synthesized only by milling for 30 hours. The X-ray
diffraction spectrum of the as-milled powders (without heating) showed twelve ZnFe2O4 peaks and
four weak peaks of coexisting unreacted Fe2O3. The crystallite size of the mechanochemicallysynthesized
ZnFe2O4 was 26.3 nm. Evidence of the ZnFe2O4 formation was absent for the powders
milled for 10 and 20 hours; milling lowered the crystallinity of the starting materials. Heating after
milling enhanced the formation of ZnFe2O4, the crystal growth of ZnFe2O4 and the unreacted
starting materials. The unreacted starting materials decreased their amounts by heating at higher
Abstract: Mg55Y15Cu30 metallic glass powders were prepared by the mechanical alloying of
pure Mg, Y, and Cu after 10 h of milling. The thermal stability of these Mg55Y15Cu30
amorphous powders was investigated using the differential scanning calorimeter (DSC).
Tg ,Tx , and Δ Tx are 442 K, 478 K, and 36 K, respectively. The as-milled Mg55Y15Cu30
powders were then consolidated by vacuum hot pressing into disk compacts with a diameter
and thickness of 10 mm and 1 mm, respectively. This yielded bulk Mg55Y15Cu30 metallic
glass with nanocrystalline precipitates homogeneously embedded in a highly dense glassy
matrix. The pressure applied during consolidation can enhance thermal stability and
prolong the existence of amorphous phase within Mg55Y15Cu30 powders.
Abstract: Recent research at Harbin Institute of Technology on the synthesis of nanocrystalline and
untrafine grained materials by mechanical alloying is reviewed. Examples of the materials include
aluminum alloy, copper alloy, Ti/Al composite, magnesium-based hydrogen storage material, and
Nd2Fe14B/α-Fe magnetic nanocomposite. Details of the processes of mechanical alloying and
consolidation of the mechanically alloyed nanocrystalline powder materials are presented. The
microstructure characteristics and properties of the synthesized materials are addressed.
Abstract: The precipitation behaviors of γ″(Ni3Nb) in four Ni-base alloys were investigated. The
four alloys were forged Ni20Cr20Fe5Nb alloy, mechanically alloyed Ni20Cr20Fe5Nb alloy, IN 718
alloy and ECAPed(equal channel angular pressing) IN 718 alloy. Aging treatment was employed at
either 600°C or 720°C for 20 hrs. The TEM observation and hardness test were performed to
identify the formation of γ″. The precipitation of γ″ was noticed after aging at 600°C for 20 hrs in
the mechanically alloyed Ni20Cr20Fe5Nb alloy and ECAPed IN 718 alloy, while it was observed
after aging at 720°C for 20 hrs in the forged Ni20Cr20Fe5Nb alloy and IN 718 alloy before ECAP.
It seemed that the lower aging temperature for γ″ precipitation in the mechanically alloyed
Ni20Cr20Fe5Nb alloy and ECAPed IN 718 alloy than in the forged Ni20Cr20Fe5Nb alloy and IN
718 alloy before ECAP appeared to be due to the severe plastic deformation which occurred during
mechanical alloying or ECAP.
Abstract: TiC particulate reinforced Fe matrix composite compacts with controlled interfacial
reaction was processed by spark plasma sintering after mechanical alloying. Milled powders were
fabricated for 1-5 hours by spex shaker mill with the ball to powder ratio of 25:2. Metal matrix
composites (MMCs) based on the Fe-40%TiC system can be synthesized by spark plasma sintering of
the D’AE powders with TiH2-graphite powders under vacuum in the temperature range 1273-1473K
for 5-20 min. TiC phase was formed by self combustion reaction with temperature increase. The
specimen that was formed by sintering Fe-TiC powders displayed a microstructure of uniformly
dispersed TiC grain in a continuous metal matrix. The densifications of the TiC-Fe materials were
increased as the heat-treatment holding time increasing. In the same time, relative density and
hardness of TiC-Fe sintering materials was increased.
Abstract: Magnesium base alloys and compounds are attractive for various applications as a
functional material. In particular, a series of binary system by Mg2X (X = Si, Ge, Sn and Pb) has
fascinated many researchers and engineers by its thermoelectric properties and semi-conductive
performance. Many barriers in its processing rejects precise investigation of these types of semiconductive
compounds: high vaporizing pressure and mechanical adhesion of magnesium, reaction
of germanium and tin with crucibles, and, difference of melting point among elements, X. Solidstate
processing via the bulk mechanical alloying enables us to directly fabricate these Mg2X semiconductive
materials in high density performs. The precise control of chemical composition leads to
an investigation on the dilution and enrichment of X in Mg2X. Two types of solid-state reactivity
are introduced: e.g. synthesis of Mg2Si from an elemental mixture Mg – Si, which is a nucleationcontrolled
process, while synthesis of Mg2Sn from Mg – Sn is a diffusion-controlled process. The
thermoelectricity of these Mg2X is evaluated for discussion on the validity and effectiveness of this
new PM route as a reliable tool for fabrication of thermoelectric compounds.
Abstract: TiC cermet is widely used for working dies with a high hardness and tool materials. In
this research, we attempted to produce submicron sized TiC powders from the ball milled TiH2 and
carbon black mixture by thermal treatment. The titanium hydride and carbon composite powders
were milled under argon atmosphere for 7 hours at various ball to powder ratios. At the initial stage,
an increase in particle size was observed, and graphite phase disappered. The TiC phase of 300nm
mean particle size was obtained by milling for 5 hours. As a result, its morphologies were
excessively agglomerated. At the heat treating temperature of 500°C, TiH2 phase transformed to Ti
completely and the complete TiC of lattice parameter 0.431 nm was formed when the temperature
reached 1000°C. Metal matrix composites(MMCs) based on the Fe-TiC system can be synthesized
by spark plasma sintering. Specimen formed sintering Fe-TiC powders display a microstructure of
uniformly dispersed TiC grain in a continuous metal matrix.
Abstract: Fe-doped TiO2 nanocrystalline powders were prepared by mechanical alloying (MA) by
varying Fe contents up to 8.0 wt.%. The TEM analyses were carried out to clarify morphologies and
position of Fe within the mechanically alloyed powders. The Fe-doped powder consisted of
spherical particles, and the average grain size was less than 10 nm. For the Fe-doped TiO2, the color
of the powders changed from white to bright yellow with increasing concentration of Fe. The UVvis
absorption showed that the UV absorption for the Fe-doped powder shifted to a longer
wavelength (red shift) and the photo-efficiency was enhanced. The absorption threshold depends on
the concentration of nano-sized Fe dopant. Mössbauer spectrum for 4 wt.% Fe showed the
ferromagnetic phase (sextet) and paramagnetic phase (doublet). However, the only paramagnetic
phase (doublet) was seen for 8 wt.% Fe. As the Fe concentration increased up to 4 wt.%, the UV-vis
absorption and the magnetization were increased. The beneficial effect of Fe doping for
photocatalysis and ferromagnetism was observed at the critical dopant concentration of 4 wt.%.
Based on the UV absorption and magnetization, the dopant level was localized to the valence band
Abstract: Ti-Cu-Ni-Sn quaternary amorphous alloys of Ti50Cu32Ni15Sn3, Ti50Cu25Ni20Sn5, and
Ti50Cu23Ni20Sn7 composition were prepared by mechanical alloying in a planetary high-energy ballmill
(AGO-2). The amorphization of all three alloys was found to set in after milling at 300rpm speed
for 2h. A complete amorphization was observed for Ti50Cu32Ni15Sn3 and Ti50Cu25Ni20Sn5 after 30h and
20h of milling, respectively. Differential scanning calorimetry analyses revealed that the thermal
stability increased in the order of Ti50Cu32Ni15Sn3, Ti50Cu25Ni20Sn5, and Ti50Cu23Ni20Sn7.