The Microstructures of Spray Formed Complex Aluminium 
Bronzes 
Klaus Ohla, Wieland — Werke Ulm, 
Gunter Benkißer, Universität Rostock 
1. Introduction 
Complex aluminium bronzes with aluminium contents up to 15 mass - % are used to 
manufacture deep drawing tools. These tools are suitable especially for the deep drawing of 
stainless steels / 1, 2 /, because low friction coefficients and low wear losses exist in the 
nm; x 1200: tribological system consisting of tool and steel. Therefore it is possible to reach a high surface 
quality of the worked sheet and a high lifetime of the tool. 
It is possible to produce rods, tubes, bars and profiles of the complex aluminium bronzes by 
use of conventional casting techniques ( e.g. sand casting, centrifugal casting ). Due to the 
high alloying content of the alloys and the unfavorable cooling conditions during the 
solidification the primary microstructure may consist out of large grains with segregated 
areas. In order to avoid problems during subsequent processing steps and to ensure an 
optimum of the product quality a special care must be taken during the casting ( e.g. 
AMPCO — Phase ™” ) to achieve a uniform grain structure. 
In the present time the spray forming is applied to the manufacture of semifinished products 
of some nonferrous alloys. In / 3, 4 / is reported on the industrial applications of the spray 
forming to the billets production ( up to 400 mm diameter and 2000 mm length ) of several 
copper alloys. The following effects of the spray forming on the microstructure are observed: 
- a grain refinement of the primary microstructure, 
- the suppression of segregations, 
- a higher regularity of the microstructure. 
In result of these structural effects it is possible, the mechanical and the tribological properties 
of convential copper alloys ( e.g. Cu — Sn alloys ) to increase and copper alloys ( e.g. Cu — Ni 
— Sn alloys or composites as Cu Sn6 with graphite particles ) with a new profile of the 
properties to produce / 3, 4 /. 
A current development consist in the spray forming of complex aluminium bronzes ( alloying 
systems Cu — Al — Fe, Mn, Ni, Co ). The purpose of the lecture consists in a presentation of 
the influence of the spray forming and the following processing steps on the formation of the 
ie ad rood microstructures of complex aluminium bronzes. 
50m rection 2. A short presentation of the spray forming 
‘ re ol In the company Wieland — Werke Ulm a production unit exists for the manufacture of billets 
our by spray forming. In Fig.1 a schematic illustration is shown of this spray forming technique. 
The holding furnace contains the melt. By the tundish and the atomizer the melt is “atomized” 
into small droplets with an average diameter of 60 pm by means of an inert gas as shown in 
I Fig.2. The gas / droplet spray cone impinges on the rotating substrate and the droplets 
Mi compact into a billet. Fig.3 shows a view in the spray chamber during the formation of the 
18 billet and after finishing of the process. 
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