166 Prakt. Met. Sonderband 38 (2006) 
The unprepared wheel-side surface of the alloy 2 is shown in Fig. 3. The as-cast surface is 
so rough that besides the surface topography no microstructural features can be unerringly 
identified (Fig. 3a). A comparison with Fig. 3b (FIB-etched for 90 min. at 10 pA) makes 
obvious, that in this case FIB-etching is not nearly that efficient as on smoother surfaces. 
Although in Fig. 3b in some areas the martensitic pattern can be clearly recognised and also 
the darker y, phase is distinct, in many places the topographical features can not be 
distinguished from the microstructural features. 
3-D microscopy 
So called in-situ 3-D imaging of alloy 1 (fully martensitic) is shown in Fig. 4. First a 2 um 
thick protective Pt-layer was FIB-deposited on the surface with the purpose to obtain a 
straight and sharp edge of the trench. The trench was sputtered with 5 nA in two hours. After 
that the cross-section was polished with 0.5 nA for an additional hour. The FIB-polished 3-D 
cross-section is shown in Fig. 4a. The brighter layer on the top of the cross-section is the Pt- 
compound protective layer. The surface below is so smooth, that the contrast of the SE 5G 
image (Fig. 4a is an electron induced SE image) is too poor to reveal the microstructure. On 
the ion induced SE image the characteristic martensitic pattern can, although with a poor 7 
contrast, be recognised without prior FIB-etching (micrograph not shown). After FIB-etching Figt 
of the cross-section area for 75 minutes with an ion current of 10 pA the contrast rich ion 
induced SE image as shown in Fig. 4b can be obtained. 
FIB 
ribb 
maj 
larg 
Fro 
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ribb 
and 
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ass 
larg 
curt 
It w 
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Figure 4: 3-D microscopy of an alloy 1 melt-spun ribbon; a) SE image after sputtering and the 
ion-polishing; b) lon induced SE image after 75 min FIB-etching at 10 pA. In 3 
adv 
The 3-D cross-section of alloy 2 was made without a Pt-protective layer. For sputtering the surf 
trench and polishing the 3-D cross-section shown in Fig. 5a the same parameters were app 
selected as in case of alloy 1 (Fig. 4a). In contrast to Fig. 4a, in Fig. 5a due to absence of Pt- sho 
protection the free surface surrounding the trench was intensively FIB-etched and the two- acc 
phase structure was well revealed. But for the same reason, in this case the edge of the 
trench is not as straight as the one in Fig. 4a and, on the cross-section itself vertical ribs 
(bright vertical lines in Fig. 5b) - the so-called curtains, also called waterfalls - are present. 
Except for the curtains an indistinctive image of the two phase structure can be seen already 
prior to FIB-etching. With increasing etching-time the phase-contrast increases. The 
micrograph in Fig. 5b was taken after 38 minutes of FIB-etching at 10 pA.