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. 2020 Aug 3;13(15):3412.
doi: 10.3390/ma13153412.

Investigation on Surface Quality of a Rapidly Solidified Al-50%Si Alloy Component for Deep-Space Applications

Oussama Chaieb  1 , Oluwole A Olufayo  1 , Victor Songmene  1 , Mohammad Jahazi  1
Affiliations

Investigation on Surface Quality of a Rapidly Solidified Al-50%Si Alloy Component for Deep-Space Applications

Oussama Chaieb et al. Materials (Basel). .

Abstract

To meet the requirements for high-performance products, the aerospace industry increasingly needs to assess the behavior of new and advanced materials during manufacturing processes and to ensure they possess adequate machinability, as well as high performance and an extensive lifecycles. Over the years, industrial research works have focused on developing new alloys with an increased thermal conductivity as well as increased strength. High silicon content aluminum (Al-Si) alloys, due to their increased thermal conductivity, low coefficient of thermal expansion, and low density, have been identified as suitable materials for space applications. Some of these applications require the use of intricate parts with tight tolerances and surface integrity. These challenges are often tied to the machining conditions and strategies, as well as to workpiece materials. In this study, experimental milling tests were performed on a rapidly solidified (RS) Al-Si alloy with a prominent silicon content (over 50%) to address challenges linked to material expansion in deep space applications. The tests were performed using a polycrystalline cubic boron nitride (PCBN) tool coated with amorphous diamond to reduce tool wear, material adhesion, surface oxidation, and particle diffusion. The effects of cutting parameters on part surface roughness and microstructure were analyzed. A comparative analysis of the surface with a conventionally utilized Al6061-T6 alloy showed an improvement in surface roughness measurements when using the RS Al-Si alloy. The results indicated that lower cutting speed and feed rate on both conventional and RS Al-Si alloys produced a better surface finish. Reduced vibrations were also identified in the RS Al-Si alloy, which possessed a stable cutting time at low cutting speeds but only displayed notable vibrations at cutting speeds above 120 m/min.

Keywords: high silicon; machining; microstructure change; milling; rapidly solidified aluminum; surface finish.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
The schematic phase diagram of Al–Si [4].
Figure 2
Figure 2
Some applications of rapidly solidified aluminum alloys [5].
Figure 3
Figure 3
Volume fraction of elements in the hypereutectic rapidly solidified (RS) alloy.
Figure 4
Figure 4
(a) Microstructure of hypereutectic RS Al–50%Si alloy and (b) HRB hardness distribution.
Figure 5
Figure 5
(a) Cracking under the effect of the tensile force on the RS Al–50%Si alloy, and (b) the cracked surface on the alloy sample.
Figure 6
Figure 6
Polycrystalline cubic boron nitride (PCBN) tool coated by PVD amorphous diamond.
Figure 7
Figure 7
HURON K2X10 CNC milling machine.
Figure 8
Figure 8
Surface integrity of a (a) 137.16 mm/min and 0.0254 mm/tooth experiment and a (b) 76.2 mm/min and 0.02032 mm/tooth experiment.
Figure 9
Figure 9
Comparison of different parameters (1) of surface roughness for the two alloys (Tool 3).
Figure 10
Figure 10
Surface roughness (Sa) vs. cutting speed and feed rate for the RS Al–50%Si alloy (Tool 3).
Figure 11
Figure 11
Roughness prediction trends from model equations. (a) at low speed of 76.2 m/min (b) at high speed of 137.16 m/min (c) at low feed of 0.02032 mm/tooth (d) at low feed of 0.0254 mm/tooth.
Figure 11
Figure 11
Roughness prediction trends from model equations. (a) at low speed of 76.2 m/min (b) at high speed of 137.16 m/min (c) at low feed of 0.02032 mm/tooth (d) at low feed of 0.0254 mm/tooth.
Figure 12
Figure 12
Average arithmetic roughness plots (a) at varying speeds for tool T1, (b) at varying feeds for tool T1, (c) at varying speeds for tool T3, (d) at varying feeds for tool T3.
Figure 12
Figure 12
Average arithmetic roughness plots (a) at varying speeds for tool T1, (b) at varying feeds for tool T1, (c) at varying speeds for tool T3, (d) at varying feeds for tool T3.
Figure 13
Figure 13
Percentage variation in roughness with a change in the cutting parameter and workpiece materials.
Figure 14
Figure 14
Evolution of the vibration as a function of the variation of (a) cutting speed and (b) feed rate for the RS Al–50%Si alloy.
Figure 15
Figure 15
Evolution of the vibration as a function of the variation of (a) cutting speed and (b) feed rate for the Al6061-T6 alloy.
Figure 16
Figure 16
Surface map and microstructure (Tool 3).
Figure 17
Figure 17
Wear observed on the cutting tool [22].
See this image and copyright information in PMC

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