Strukturne i termijske karakteristike mehanohemijski tretiranih metalnih prahova
Structural and thermal characteristics of mechanochemically treated metal powders
Author
Zdujić, Miodrag V.
Mentor
Poleti, Dejan
Committee members
Skala, Dejan
Radmilović, Velimir

Karanović, Ljiljana

Metadata
Show full item recordAbstract
U ovom radu je ispitivano dobijanje neravnotežnin struktura u metalima
mehanohemijskim tretmanom. Strukturne i termijske karakteristike prahova mehanohemijski
tretiranih različito vreme mlevenja su ispitivane rendgenskom strukturnom analizom,
diferencijalnom skanirajućom kalorimetrijom, diferencijalnom termijskom analizom, kao i
skanirajućom i transmisionom elektronskom mikroskopijom. Eksperimentalni rezultati su
diskutovani sa kinetičkog i termodinamičkog stanovišta.
Mehanohemijski tretmani, tj. mehaničko legiranje smeša čistih prahova aluminijuma i
molibdena različitih početnih sastava (Al-0, 3, 10, 17, 20, 27, 50, 75 i 100 at.%Mo) su rađeni u
horizontalnom kugličnom mlinu. U svim sličajevima mlevenje proizvodi nanokristalnu i/ili
amorfnu strukturu. Tokom naknadnog termijskog tretmana, ovakvi metastabilni proizvodi lako
reaguju obrazujući intermetalna jedinjenja: Al12Mo, Al5Mo, Al4Mo, AlgMo3 i AlMo3.
Smesa prahova nikla i molibdena (Ni-50 at.%Mo) je mlevena u različitim tipovima
mlin...ova. Mehaničkim legiranjem u horizontalnom kuglicnom mlinu dobija se amorfna faza. U
planetarnom i vibracionom mlinu, zbog veće energije mlevenja, dobija se neuređeno
intermetalno jedinjenje.
Mehanohemijska reakcija amortizacije u oba ispitivana sistema je slična i odvija se u
četiri stupnja: (i) obrazovanje veoma finog kompozitnog praha, (ii) obrazovanje čvrstog
rastvora Al(Mo) ili Ni(Mo), (iii) transformacija presićenog čvrstog rastvora u amorfnu fazu i (iv)
postepeno rastvaranje zaostalih kristalita molibdena u amorfnoj matrici.
In this study the formation of non-equilibrium structures in metals by mechanochemical
treatment has been investigated. The structural and thermal properties of powders
mechanochemically treated for various milling times have been studied by X-ray
diffraction, differential scanning calorimetry, differential thermal analysis, as well as
scanning and transmission electron microscopy. The experimental results were
discussed from kinetic and thermodynamic point of view.
Mechanochemical treatment, i.e. mechanical alloying of mixture of aluminium and
molybdenum powders of various starting compositions (Al-O, 3, 10, 17, 20, 27, 50, 75
and 100 at.%Mo) was performed in a horizontal ball mill. In all cases milling produced
nanocrystalline or/and amorphous structures. During subsequent heat treatment such
metastable products easily react leading to the formation of intermetallic phases:
Al12Mo, Al5Mo, Al4Mo, Al8Mo3 and AlMo3.
Mixture of nickel and molybdenum powders (Ni-50 at.%Mo) was treated in ...various
types of mills. Mechanical alloying in the horizontal ball mill yields an amorphous phase
while in planetary and vibrating ball mill a disordered intermetallic compound was
produced as a result of greater milling energies.
The formation of amorphous phase in both systems is similar and occurs in four
stages: (i) formation of very fine composite powders, (ii) formation of solid solution
either Al(Mo) or Ni(Mo), (iii) collapse of supersaturated solid solution into the
amorphous phase and (iv) gradual dissolution of residual molybdenum crystallites into
the amorphous matrix.