Fig. 3.1 Schematic diagram of the apparatus to pull single crystals of rare earth intermetallic compounds
In this chapter we list various investigations that
have to do with material preparation and properties of materials.
Elastic constants
The strength of the interaction of dislocations with impurities in metals
partially depends on the change of elastic constants with impurity concentration.
Therefore, it is of considerable interest to know about the change of these
constants with concentration. On this background, the following work has been
performed [1]:
Preparation of single crystals of Ag-Al and Ag-Au by
the Bridgeman method and control of the quality of the crystals using standard
methods from metallurgy.
Determination of the elastic modules of rods of Ag-Al and Ag-Au
single crystals being oriented in <100>, <110> and <111> crystallographic
direction and evaluation if all three single crystal elastic constants as a
function of the impurity concentration.
The results are analysed in terms of a simple theoretical model.
Also in the context of the plastic deformation of Ir single crystal
are of interest. Therefore, for the first time the single crystal modules have
been determined of this metal. Thereby the single crystals were prepared by
the zone melting technique. This work is considered as one of the highlights
in the field of material science [2].
Single crystals
Another highlight is the first preparation of single
crystals of rare earth intermetallic compounds [4]. Thereby the Bridgeman technique
has been applied using a tungsten crucible and appropriate germs to define the
crystallographic orientation of the final crystal. The diameter of the latter
measured about 1 cm und the length of the crystals was of the order of some
cm. The technique was describe somewhat later also in [9]. We mention that the
work on the magnetic properties of rare earth intermetallic compounds, to large
extent, is based the availability of such crystals.
Electrical resistivity
Finally, we mention that several attempts have been made to
get a deeper understanding of the low temperature resistivity of alloys in the
context of so called spin-fluctuations [5,6,8].
