In order to rise the wear and corrosion resistance of 0.45% C superficial steel layers, a multilayer coating was tested by injection of powder with 88.3% Cu; 9.5% Al; 2.2% Fe in melted bath by CO2 continuous wave laser. Layers made by different laser conditions were characterized by macro and microstructure analysis, phase quality analysis, by X ray diffractometry and microhardness analysis. Research was carried out regarding the importance of nickel alloy intermediary layer for the rising of cladding quality

Simona BOICIUC

The Annals of “Dunarea de Jos” University of Galati Fascicle IX Metallurgy and Materials Science

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THE ANNALS OF “DUNAREA DE JOS” UNIVERSITY OF GALATI. 
FASCICLE IX. METALLURGY AND MATERIALS SCIENCE 
No. 3 - 2015, ISSN 1453 – 083X 
 
 
 
LASER DEPOSITION OF BRONZE ALUMINUM  
ON STEEL SUPPORT 
 
Simona BOICIUC 
,,Dunarea de Jos” University of Galati 
e-mail: simonaboiciuc@yahoo.com 
 
ABSTRACT 
 
In order to rise the wear and corrosion resistance of 0.45% C superficial steel 
layers, a multilayer coating was tested by injection of powder with 88.3% Cu; 9.5% 
Al; 2.2% Fe in melted bath by CO2 continuous wave laser. Layers made by different 
laser conditions were characterized by macro and microstructure analysis, phase 
quality analysis, by X ray diffractometry and microhardness analysis. Research was 
carried out regarding the importance of nickel alloy intermediary layer for the 
rising of cladding quality. 
 
KEYWORDS: laser cladding, aluminum bronzes, microstructure, 
microhardness, diffractometry. 
 
1. Introduction 
 
Biphasic aluminum bronzes are known for their 
outstanding wear resistance, cavitation, corrosion etc., 
widely used in naval, petrochemical, chemical 
industry, etc. (bearings, rods, valve, pump impellers, 
and compressor screws and rotors, etc.). 
 Copper alloys with 9-11% Al feature, in 
addition to high corrosion resistance, good casting 
and hot forming properties and heat treatment 
hardening capacity of martensitic quenching and 
tempering. 
According to the equilibrium diagram, Cu-Al 
alloys have balanced structure consisting of plastic 
solid solution  and eutectoid ( + 2), where 2 is a 
solid hard and brittle solution based on the electronic 
Cu32Al19, compound. 
Classical quenching consists of [1-3] heating at 
temperatures of 980-1000 °C in the  solid solution 
range based on the Cu3Al, electronic compound, 
followed by rapid cooling in water. According to the 
thermal kinetic diagram, at higher cooling rates there 
is a diffusion transformation, with the solid solution 
ordering  -> 1, after which the diffusion-free 
transformation of phase 1 occurs in a needle-type 
martensite structure ' [1-3]. 
This structure has a relatively low hardness due 
to the coarse grain formed at high temperatures and in 
the presence of phase . Subsequent tempering at 
400-550 °C causes reverse transformations: '->1 
and 1 phase decomposition in a dispersed mixture  
+ 2, having hardening effect. 
Thus the CuAl10Fe4Ni4 alloy after quenching 
from 980 °C in water and tempering at 400 °C, 
increases its hardness from 170-200 HB to over 400 
HB. 
In the special Cu-Al alloys there are additions of 
Fe, Ni, Mn, which change the solubility of aluminum 
in copper and lead to new phases. Iron polishes 
granulation and improves mechanical and antifriction 
properties. In Fe-rich alloys an intermetallic 
compound FeAl3 may occur with hardening and 
embrittlement effect. Nickel and manganese increase 
corrosion resistance and provide further hardening by 
solid solution alloying. 
Laser heating has the advantage that it provides 
very fast heating rates (over 103 °C/s) at high 
temperatures and similar cooling speed, which allows 
hardening of aluminum with bronze both in liquid 
and solid phases while maintaining an ultrafine 
granulation [4-8]. Laser surface quenching, however, 
has the disadvantage of relatively small thickness of 
the hardened layer, a certain variation of the 
properties of the hardened layer depth and the need 
for subsequent tempering [9-11]. 
Multilayer deposition of aluminum bronze 
powders injected onto the laser melted surface has the 
advantage of making thick layers with uniform 
chemical composition and properties throughout the 
section. 
This paper presents laboratory experimental 
research on multilayer deposit on a steel support by 
injecting biphasic aluminum bronze powders in a 
laser molten bath. 
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THE ANNALS OF “DUNAREA DE JOS” UNIVERSITY OF GALATI. 
FASCICLE IX. METALLURGY AND MATERIALS SCIENCE 
No. 3 - 2015, ISSN 1453 – 083X 
 
2. Experimental conditions 
 
2.1. Sample preparation 
 
For coating, use was made of a two-phase 
aluminum bronze powder, capable of hardening by 
quenching. Table 1 shows the origins, chemical 
composition and particle shape of the addition 
materials. The powder was aspherical, so that fluid 
flowing on the surface of processed addition material 
was stimulated by vibration. Since the coating with 
aluminum bronze on the steel support indicated a low 
quality of the deposited layers geometry (rough 
surface, thin deposit and micro-cracks), its deposition 
on a buffer layer of nickel alloy was experienced and 
a very good deposition on steel substrate was found. 
Coatings were made on samples of 25 x 25 x 15 
mm of 0.45% C normalized carbon steel. 
 
Table 1. Characteristics of the added materials used 
 
Nr. 
crt. 
Type of added material 
Chemical composition of 
added material 
Grain shape 
1 
Nickel alloy „Alliages 
Speciaux 7569 ALLIAGES 
FRITTÉS, Franţa”. 
8.9% Cr; 4.5% Fe; 5.1% B; 
2.4% Al; 0.6% Cu; rest Ni. 
 
2 
Bronze with alluminum 
,,Rototec Proces FRIXTEC 
CASTOLIN U.S.A.”. 
9.5% Al; 2.2% Fe; rest Cu. 
 
 
Laboratory experiments were conducted on a 
CO2 continuous wave laser facility type GT with 
power of 1400 W, with coordinate table and computer 
for the process control, equipped with a powder 
injection system on the support surface. 
Laboratory tests used a 1.8 mm diameter laser 
beam, which made partially overlapping parallel 
strips. The final thickness of the layer was achieved 
by superposition of five layers. 
To determine the optimum deposition regime, 
the added material flow rate was varied, Q, from 53 to 
150 mg/s, beam power, P, from 900 to 1200 W, 
surface scanning speed, v, from 5-7 mm/s and 
transverse movement step, p, 1 to 2 mm. 
The nickel alloy buffer layer was deposited by 
the superposition of two layers, under the following 
conditions: Q = 53 mg/s, P = 1100 W, v = 7 mm/s, p 
= 1-2 mm. Table 2 shows the experimented working 
regimes and thickness, h, of the deposits obtained. 
Deposition regime was characterized by energy 
density factor K = P / d * v, which ranged within 79.3 
÷ 100 J/mm2. 
2.2. Structural properties 
 
Initially deposited layers were characterized by 
macroscopic analysis of the surface layer deposited. 
Microstructural analysis was performed on samples 
cross-section, perpendicular to the direction of laser 
processing. 
The microstructure of the samples was observed 
by optical microscopy Olympus BX 51M. 
For the phase qualitative analysis of the surface 
layer deposited, use was made of the diffractometer 
DRON 3 with copper anti-cathode, monochromatic 
diffraction beam, U = 34 kV, I = 30 mA; F1 = 2 mm; 
F2 = 0.5mm; ω = 1/min; vstrip = 720 mm/h for the 
diffraction angle variation within 2 = 20°....75°. 
 
2.3. Microhardness depth profile 
measurement 
 
It was determined the microhardness profile 
HV0,1 (0.98N load) over the depth of the deposited 
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THE ANNALS OF “DUNAREA DE JOS” UNIVERSITY OF GALATI. 
FASCICLE IX. METALLURGY AND MATERIALS SCIENCE 
No. 3 - 2015, ISSN 1453 – 083X 
 
layers. Microhardness depth profiling measurements 
were performed using a PMT-3 apparatus. 
Vickers microhardness was calculated according 
to the SR EN ISO 6507-1:2002 standard. Results are 
presented as a mean of three measurements. 
 
3. Results and discussions 
 
3.1. Structural properties 
 
Macroscopic analysis highlights the deposited 
layer surface quality, thickness and adhesion to the 
support. 
The macrostructures of the laser deposition of 
aluminum bronze show a low adhesion to the carbon 
steel support, which can be explained by the poor 
metal link due to the low solubility of solid copper in 
iron. 
The surface layer is rough (Fig. 1) and requires 
subsequent removal by machining of a relatively 
large layer. Inside the layers, solidification shrinkage 
cracks have appeared. The coating is hardened and 
made brittle by diffusion of iron from the base 
material into the added material and formation of the 
compound FeAl3. 
 
Table. 2. Experimental conditions and deposited layer thickness 
 
Sample 
code 
Q 
[mg/s] 
P 
[W] 
v 
[mm/s] 
K  
[J/mm2] 
P 
[mm] 
h 
[mm] 
Observations 
Bronze aluminum deposition on steel support 
1 86 1000 7 79.36 2 0.38 C 
2 86 1100 7 87.30 2 0.5 C 
3 110 900 7 71.42 2 0.16-0.54 C, N 
4 150 900 5 100.00 2 0.06-0.49 C, N, E 
5 150 1100 7 87.30 2 0.13-1.00 C, N 
6 119 1100 7 87.30 2 0.08-1.23 C, N 
7 119 1200 7 95.24 2 0.14-1.21 C, N 
Bronze aluminum deposition on steel support, with middle nickel alloy layer 
8 53 1100 7 87.30 2 0.47 - 
9 53 1100 7 87.30 1.5 0.74 - 
10 53 1100 7 87.30 1 0.64 - 
Note: C-cracks; N-non uniformities of the layer thickness, E-exfoliation 
 
From Table 2 and Figure 1, it can be seen that 
the non-uniform thickness of the layer deposited 
under the same conditions and the surface roughness 
increase with increasing the added material flow rate 
over 86 mg/s (sample code 2, 5 and 6). This is 
explained by the increased added material flow rate 
under the same conditions of laser processing, the 
molten bath temperature decreases by additional 
energy consumption for heating and melting the 
powder, which increases the viscosity of the molten 
added material. With lower laser beam powers and 
higher flow rates, there is insufficient melting of the 
support material and lack of adhesion of the deposited 
layers (sample code 4). With the same added material 
flow rate, the layer thickness increases with higher 
laser beam power, more pronounced at higher flow 
rates (sample code: 1 and 2, 4 and 5). These 
macroscopic observations indicate that the samples 
code 1...7 show no practical interest. 
The decrease in the added material flow rate to 
53 mg/s and the use of a buffer layer of nickel alloy, 
unlimitedly soluble as solid in both iron and copper, 
increased the adhesion to the steel support and to the 
deposited layer. The layer quality was significantly 
improved as this becomes uniform, compact, without 
solidification shrinkage cracks and with practical 
applicability. Note that when using a 1.8 mm 
diameter laser beam on the surface being processed, 
the max. layer thickness is obtained on a step of the 
transverse movement of the 1.5 mm sample. 
Figures 2 and 3 show the microstructure of the 
deposited layer for samples code 1 and 10. Good 
support adherence of the deposited layer is visible. At 
the fusion limit there are no compactness defects or 
inclusions of metal. When coating is directly 
performed on steel support, the presence of transverse 
cracks is initiated at the solidification surface (Fig. 
2a), while by using the buffer layer of nickel alloy, 
the deposited layer is compact and crack-free (Fig. 
3a). 
The microstructure of the deposited layer results 
from melting and ultra-fast solidification of the added 
material, followed by a partial self-tempering in the 
overlapping area of the strip deposited i.e. sub-layer 
tempering when an additional layer is deposited. 
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THE ANNALS OF “DUNAREA DE JOS” UNIVERSITY OF GALATI. 
FASCICLE IX. METALLURGY AND MATERIALS SCIENCE 
No. 3 - 2015, ISSN 1453 – 083X 
 
 
 
 
Fig 1. Macroscopic aspect of some thick bronze-aluminium samples 
 
 
 
Fig. 2. Microstructure of the deposited layer with sample code 1 without Ni alloy middle layer a), 
general view x500; b). Middle of the deposited layer x1000; c). Base of the deposited layer x1000.  
Ferric chloride attack 
 
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THE ANNALS OF “DUNAREA DE JOS” UNIVERSITY OF GALATI. 
FASCICLE IX. METALLURGY AND MATERIALS SCIENCE 
No. 3 - 2015, ISSN 1453 – 083X 
 
 
 
Fig. 3. Microstructure of the deposited layer with sample code 10 with Ni alloy middle layer a). 
Middle part of the deposited layer x1000; b). Base of the deposited layer x1000.  
Ferric chloride attack 
 
For example, with sample code 1, the basic 
microstructure is fine columnar dendritic, at certain 
points with needle type appearance specific to 
hardening martensitic structures with coarse 
interdendritic separation of an intermetallic 
compound according to the diffraction diagram for 
the qualitative phase analysis of the deposited layers 
(Fig. 4). In the copper-based solid mass solution there 
is the interdendritically separated compound Fe - Al 
(Fig. 2b). The occurrence of relatively large quantities 
of compound is because the 2.2% Fe content in the 
added material is added to the iron by melting a steel 
substrate. Initiation and propagation of transverse 
shrinkage cracks upon solidification can be accounted 
for by the hard and brittle compound. At the base of 
the deposited layer there is a small thickness dilution 
layer which makes the transition to the steel support 
with a small amount of Fe-Al compound. With the 
sample code 10, the microstructure is similar to a 
smaller amount of intermetallic compound – K - 
phase-intermetallic compound of Fe, Al, Ni (Fig. 5) 
with rosette aspect, because the layer of molten nickel 
alloy, which alloys the filler material, had a smaller 
amount of iron and the nickel presence slows the 
diffusion processes upon compound separation. 
Additional nickel alloying of the added material 
led to a solid solution of copper, more resistant to 
metallographic attacks. 
The unlimited solubility of copper and the 
nickel bases of the added material and buffer do not 
allow for the creation of a buffer zone separating the 
two deposits. 
 
 
 
Fig. 4. Diffractogram for the layer cladded for sample code 1 
 
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THE ANNALS OF “DUNAREA DE JOS” UNIVERSITY OF GALATI. 
FASCICLE IX. METALLURGY AND MATERIALS SCIENCE 
No. 3 - 2015, ISSN 1453 – 083X 
 
 
 
Fig. 5. Diffractogram for the layer cladded for sample code 10 
 
3.2. Microhardness depth profile 
measurement 
 
Figure 6 shows the variation of microhardness 
HV0.1 over the depth of the layer deposited on the 
sample code 1 and 10. Microhardness maximum 
corresponds to a sample code 1, due to the presence 
of FeAl3 compound in large amount and due to the 
stability of the martensitic structure to the quick 
tempering process. 
The layers obtained with nickel alloy buffer 
layer have less hardness because nickel reduces the 
amount of intermetallic compound and increases the 
amount of the additionally alloyed solid solution of 
copper. Microhardness is maximal in the buffer layer 
of the nickel alloy with higher thermal stability. 
 
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
0,15 0,65 1,15 1,65 2,25
distance from the surface [mm]
m
ic
ro
h
a
rd
n
e
s
s
 H
V
0
,1
 [
M
P
a
]
sample 1 sample 10
 
 
Fig. 6. Variation of microhardness HV0.1 over the depth of the layer deposited 
on the sample code 1 and 10 
 
Comparing the microhardness of the multilayer 
deposit by laser with the properties of the aluminum 
bronzes, laser hardened in the liquid phase and 
tempering [5-7], it was found that laser deposition 
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THE ANNALS OF “DUNAREA DE JOS” UNIVERSITY OF GALATI. 
FASCICLE IX. METALLURGY AND MATERIALS SCIENCE 
No. 3 - 2015, ISSN 1453 – 083X 
 
resulted in higher microhardness and greater depths. 
This is due to alloying bronze with nickel and iron, to 
the finer microstructure and the self-tempering 
process. 
 
4. Conclusions 
 
Multilayer deposition by aluminum bronze 
powder injection into the laser melted bath on steel 
base presents difficulties because of the poor 
adhesion of the deposit to the steel support, the non-
uniformities of the deposited layer and shrinkage 
cracks. The coating is hardened and made brittle by 
diffusion of iron from the base material into the added 
material and by the formation of FeAl3 compound. 
Non-uniformity of the deposition increases with 
the deposit filler flow rate over 86 mg/s and lower 
laser beam power, below 1000 W. 
Introducing a buffer layer of nickel alloy has 
improved adhesion, thickness uniformity and 
compactness of the aluminum bronze deposited 
layers. The optimum deposition regime was nickel 
alloy middle layer, regimes 9 and 10, which ensured a 
0.64 to 0.74 mm thick layer with a microhardness 
HV0,1 ranging between 3895 and 3406 MPa. 
Multilayer deposit ensures self-tempering of the 
layer and provides a superior microhardness at depths 
greater than the liquid phase quenching of aluminum 
bronzes of similar chemical composition. 
 
 
References 
 
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lasers, Thesis, Shell Research and Technology Centre, Amsterdam, 
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[3]. Levcovoci S. M., Levcovici D. T., Paraschiv M. M., Laser 
Hardening of Aluminum Bronzes, Materials and manufacturing 
processes, vol. 17, p. 13-22, 2002. 
[4]. M. F. Schneider, Laser cladding with powder, Ph. D. Thesis 
University of Twente, Enschede, Olanda, 1998. 
[5]. H. Gedda, Laser surface cladding - a literature survey, Lulea 
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[9]. S. Levcovici, D. T. Levcovici, C. Gheorghieş, S. Boiciuc, 
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[10]. S. Boiciuc, S. Levcovici, D. T. Levcovici, C. Gheorghies, 
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[11]. S. Boiciuc, et al., EDX Analysis of Laser Cladding Layers 
with Ni-Cr-B-Fe-Al Alloy, Conference UgalMat, Galati, Romania, 
2009. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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Laser Deposition of Bronze Aluminum on Steel Support

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Laser Deposition of Bronze Aluminum on Steel Support

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