HONS ot
re Sate N
Fe x Fas B75 TRNAS Sp SRR a
ae ER re Ts
EZ ET EN LE
ARE PN
ew red PRES SFIS KT re ze
N
Wo Pi An A ) tr
ie: SAN, SW 100m
Figure 6: Microstructure of the spray formed and hot pressed alloy ( longitudinal section ), banded structure
of the former PB — grains, rosette — like particles of the y, — phase in the B; — matrix, finedisperse « -
precipitations
In Fig. 4 the microstructure of the spray formed alloy Cu Al14 Fe Mn Co is presented. The
microstructures of the spray formed alloy and of the cast alloy ( Fig. 3 ) are similar. However
the amount of the y, — phase in the microstructure of the spray formed specimen is a little
smaller compared with the cast alloy. It is possible to explain this fact by the higher
aluminium content of the cast alloy. The lower diagram of Fig. 5 shows the X — Ray
diffraction pattern of the spray formed alloy. The reflections of the y, — phase and of the f; —
phase are observed.
By hot pressing a grain refinement and a banded structure of the former — grains are
produced as shown in Fig. 6. The microstructure consists also of the phases v2, 1 and x.
However the y, — particles have a smaller size compared with the y; — particles in the spray
formed state ( Fig. 4).
It is possible to describe the formation of the microstructure of the casting and the spray
formed specimens by the following transformations:
Melt —> bccß >ß+Kk—>ßB+K+y2 > Ph+tntka>PBi+tyatx
3.2 Influence of the betatization on the microstructure
The described betatization produces an almost complete stabilization of the ordered bee
B, — phase ( Cu Al). Fig. 7 shows the coarse - grained microstructure of the cast alloy after
the betatization ( 950°C / 30 minutes / oil quenching ). In the Bf; — matrix small particles of
incomplete dissolved or new generated k — phase are observed. In the X — ray diffraction
pattern the reflections of the ordered B, — phase are predominant ( Fig. 9, upper diagram ).
Some small peaks indicate to the presence of a little amount of the ordered orthorhombic f3, —
phase. It is possible to describe the formation of the microstructure by the following reactions.
Melt — bee B + k — ordered bee B, + tracks of the ordered orthorhombic 1 — phase + x
rym SO
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