Fabrication of Al6061 composite with high SiC particle loading by semi-solid powder processing
Introduction
Semi-solid powder processing (SPP) combines the advantages of powder metallurgy and semi-solid forming [1], [2], [3], [4], [5], [6], [7]. In contrast to traditional bulk semi-solid forming, the process enables the mixing of various powders for improved properties and eliminates post-processing steps required for powder metallurgy routes. A summary of various processing routes of SPP investigated by other researchers is shown in Fig. 1 [8], [9], [10], [11], [12], [13], [14], [15], [16], [17]. In general, four basic steps are involved in SPP: powder preparation, powder precompaction, heating and semi-solid forming. SPP has been applied to produce net-shaped metal matrix composites (MMCs) with low reinforcement loading (<30%). Previous work has demonstrated the potential to produce composites with high efficiency, low cost and good compositional control with promising microstructures [18], [19], [20], [21].
Although it has been more than 20 years since the introduction of SPP, no in-depth research has been conducted concerning high reinforcement loading conditions above 45 vol.%. Metals reinforced with high reinforcement loading is very attractive due to the modified properties such as high modulus and strength, low coefficient of thermal expansion, and improved thermal conductivity [22], [23], [24]. Methods including infiltration [25], [26], [27], casting [28], [29], [30], and powder metallurgy [31] have been investigated to fabricate metal matrix composites reinforced with high ceramic loadings. Several limitations were discussed as to the fabrication of high ceramic loading MMCs, such as difficulty in compositional control in casting, sintering balance [32] and ceramic powder percolation [33], [34] in powder metallurgy, and closed and half closed pore problems in infiltration casting [35], [36], [37], [38], [39].
In this paper, a matrix phase of aluminum alloy 6061 (Al6061) reinforced by silicon carbide (SiC) particles was used to understand the synthesis of composites with reinforcement loadings above 45 vol.% by SPP. Theoretical SiC loading limit of the SPP has been proposed and discussed. In addition, effects of processing parameters, which include SiC loading, applied pressure and matrix-reinforcement particle size, on microstructure and hardness have been studied.
Section snippets
Experimental procedures
The Al6061 powders and SiC particles were prepared by blending in a powder mixer (SPEX 8000M) for 8 min. The chemical composition of Al6061 powders obtained from Valimet Inc. is shown in Table 1. The size and distribution of Al6061 and SiC particles (AEE Inc.) are summarized in Table 2. The experimental setup for heating and compression is shown in Fig. 2. The die and powders were heated in the furnace (Applied Test System Inc.), while the load and movement of upper ram were controlled and
Results and discussion
The compaction curves of SPP are analyzed to understand the synthesis mechanism of Al6061–SiC composite and the SiC loading limit. Then, effects of processing parameters on the composite microstructure, hardness and fracture surface are discussed. In addition, the presence of aluminum carbide (Al4C3) is checked with X-ray diffraction analysis.
Conclusion
In this paper, SPP was used to fabricate Al6061 composite reinforced with high volume loading of SiC particles. The compaction and synthesis mechanism of Al6061–SiC composite was discussed, and the SiC loading limit was analyzed. The effects of the reinforcement particle size, matrix particle size, reinforcement loading volume and pressure on the microstructure and mechanical properties were investigated.
SPP of Al6061 composite for high loading SiC conditions had the following characteristics.
Acknowledgements
The authors greatly appreciate the financial support from the Ames Laboratory of US Department of Energy. Ames Laboratory is operated for the US DOE by Iowa State University under contract No. DE-AC02-07CH11358.
References (46)
- et al.
J Manuf Sci Eng Trans ASME
(2007) - et al.
J Mater Process Technol
(2005) - et al.
J Mater Process Technol
(2001) - et al.
Compos Part A: Appl Sci Manuf
(2003) - et al.
Trans Nonferr Met Soc China
(2006) - et al.
Mater Sci Eng A
(2005) - et al.
Compos Sci Technol
(2000) Mater Sci Eng B
(1998)- et al.
Mater Sci Eng A – Struct Mater Proper Microstruct Process
(2004) - et al.
Mater Sci Eng A – Struct Mater Proper Microstruct Process
(2008)
Mater Sci Eng A – Struct Mater Proper Microstruct Process
Acta Mater
Compos Sci Technol
Ceram Int
Compos Part B Eng
Mater Sci Eng A Struct Mater
Mater Sci Forum
Acta Mater
Mater Sci Eng A
Acta Mater
Mater Sci Eng A
Acta Mater
Acta Mater
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