162 Prakt. Met. Sonderband 38 (2006) 
Therefore they exhibit the shape memory effect when the temperature during hot mounting If th 
is changing in the range of the alloys transformation temperatures. The samples change will 
their shape or, if hold in clamps, very likely breaks apart. Cracks in our hot mounted and 
samples were often observed, especially in alloys with relatively high Al-contents. In the be 
case of cold mounting, during polymerization, the temperature can also reach the level of inci 
the alloy’s transformation range. Additionally, gaps between the sample and the resin stru 
occur quite frequently, from which the etchant is extremely hard to remove. In our mat 
experience good universal etchants which reveal the phase composition, as well as the Au 
martensitic pattern, contain quite aggressive and volatile ingredients like (NH4),S,0g and Spu 
HCI. Consequently, it is very difficult to find the optimal dilution and to reproduce the FIB 
results even within a few hours. They must be examined immediately after etching (inte 
otherwise the remnant etchant from the almost always present gaps can damage the fail 
sample before examination. All these facts stimulate the search for alternative preparation By 
techniques. One of the most promising methods seems to be preparation using the IC 
focussed ion beam (FIB). trar 
The FIB systems, in principle, work in the same way as the electron beam systems. Both of | 
consist of an emission source (electron or ion source), lens column, work stage, vacuum rea 
and control systems. lon optics is very much like electron optics. Electrons and ions are both opti 
charged particles and can be focussed by electromagnetic fields into a fine beam. The only tool 
difference is that ions can have different masses and charges. imp 
During the scattering process ions lose their energy and eventually stop somewhere in the for 
solid target material (sample). Elastic scattering changes the direction of the incident ion 5, € 
without a loss of energy, inelastic scattering causes loss of energy in two ways. One is of 
nuclear loss, i.e. an incident ion collides with an atomic nucleus causing the atom either tha 
dislocating its position to become a recoil atom or escaping from the solid surface. The (FI 
phenomenon knocking atoms out of solid targets is called sputtering. The other type is be 
electronic loss, i.e. the incident ion transfers a part of its energy to the electrons. These do 
electrons can either be excited to produce secondary electron emission or be stripped of ma 
the atom resulting in the ionisation of atoms and secondary ion emission. The penetration SCE 
depth (stopping range) of incident ions increases with the ion energy and decreases with dra 
increasing ion-mass and solid atom relative atomic mass. Some incident ions after loosing apr 
all their energy will become a part of the material (implantation) which can modify the 
material's local chemical composition. If this is done on purpose it is called doping. 
Scattering in an amorphous target material is a random process. In crystalline materials, 2 
along the low indexed axis of crystalline incident ions can penetrate several times deeper 
as in other directions or amorphous targets. This phenomenon is called ion-channelling To 
effect and decreases the yield of sputtered target atoms. Therefore sputtering rates on allc 
polycrystalline surfaces can be very uneven. lon bombardment can also result in the (all 
amorphisation of the surface layer. in 1 
It was revealed that the ion sputtering yield has the following features [1]: The sputtering wh 
yield rises with the beam incident angle (angle from the vertical incidence) and reaches the foll 
maximum at about 80°. For gallium ions, the sputtering yield is increasing with increasing alle 
ion-energy only up to 30 keV (yield saturation). The number of re-deposited atoms um 
increases with the deepness of the sputtered hole and with the decrease of the scanning eq 
speed. Efficient way to reduce the re-deposition rate is to sputter with fast multiple scan of e: 
the ion beam. lon bombardment combined with chemically active gases can multiply the 
sputtering rate. A small amount of a chemically active gas is introduced into a chamber, 
where the gas molecules adhere to the target surface. lon bombardment ionises the gas 
atoms and the gas ions react with the target-atoms to form volatile compounds, which are 
then evacuated by the vacuum system. Appropriate reactive gas must be applied for every 
target material.