PSI - Issue 23

Petr Haušild et al. / Procedia Structural Integrity 23 (2019) 179–184 Haušild et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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3

FeAl25 (75%), Si (25%) FeSi25 (75%), Al (25%)

FeAl_Si FeSi_Al Fe_AlSi

Fe (60%), AlSi30 (28.5%), Si (11.5%)

1h

2h

8h

Fig. 1. Microstructure inside the individual particles after milling elemental (Fe_Al_Si) feedstock powders for different time (SEM, back-scattered electron signal).

In order to assess the values of hardness of individual mechanically alloyed powder particles, maximum load of 2 mN was used. The conditions for indentation not affected by surrounding embedding resin were optimized by an extensive experimental study and finite element method computations in previous research (Haušild et al. (2018b), Čech et al. (2019)).

3. Results and discussion

Typical example of evolution of microstructure after mechanical alloying is shown in the Fig. 1. In the beginning of milling, the rapid fracturing and cold welding occurs and convoluted lamellae can be observed within the particles. With increasing time of milling, convoluted lamellae get finer and the almost complete solid solution was reached after about 6-8 h of milling. No substantial differences in the character of microstructure could be observed comparing the batches prepared from elemental powders and from pre-alloyed powders.