Ultrasonic Attenuation Based Inspection Method for Scale-up Production of A206–Al2O3 Metal Matrix Nanocomposites
01 Feb 2015-Journal of Manufacturing Science and Engineering-transactions of The Asme (American Society of Mechanical Engineers)-Vol. 137, Iss: 1, pp 011013
TL;DR: In this article, the relationship between the ultrasonic attenuation and the microstructures of pure A206 and Al2O3 reinforced MMNCs with/without ultrasonic dispersion was investigated.
Abstract: A206–Al2O3 metal matrix nanocomposite (MMNC) is a promising high performance material with potential applications in various industries, such as automotive, aerospace, and defense. Al2O3 nanoparticles dispersed into molten Al using ultrasonic cavitation technique can enhance the nucleation of primary Al phase to reduce its grain size and modify the secondary intermetallic phases. To enable a scale-up production, an effective yet easy-to-implement quality inspection technique is needed to effectively evaluate the resultant microstructure of the MMNCs. At present the standard inspection technique is based on the microscopic images, which are costly and time-consuming to obtain. This paper investigates the relationship between the ultrasonic attenuation and the microstructures of pure A206 and Al2O3 reinforced MMNCs with/without ultrasonic dispersion. A hypothesis test based on an estimated attenuation variance was developed and it could accurately differentiate poor samples from good ones. This study provides useful guidelines to establish a new quality inspection technique for A206–Al2O3 nanocomposites using ultrasonic nondestructive testing method.
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TL;DR: It was found that besides of growth restriction factor by pinning behavior on grain boundries, TiC nanoparticles served as both an effective nucleation agent for primary grains and an effective secondary phase modifier in AA7075, and the mechanical properties of nano-treated aluminum alloys were improved over those of the pure alloy.
Abstract: Nano-treating is a novel concept wherein a low percentage of nanoparticles is used for microstructural control and property tuning in metals and alloys. The nano-treating of AA7075 was investigated to control its microstructure and improve its structural stability for high performance. After treatment with TiC nanoparticles, the grains were significantly refined from coarse dendrites of hundreds of micrometers to fine equiaxial ones smaller than 20 μm. After T6 heat treatment, the grains, with an average size of 18.5 μm, remained almost unchanged, demonstrating an excellent thermal stability. It was found that besides of growth restriction factor by pinning behavior on grain boundries, TiC nanoparticles served as both an effective nucleation agent for primary grains and an effective secondary phase modifier in AA7075. Furthermore, the mechanical properties of nano-treated AA7075 were improved over those of the pure alloy. Thus, nano-treating provides a new method to enhance the performance of aluminum alloys for numerous applications.
35 citations
TL;DR: In this paper, the influence of SLM processing parameters, especially laser scan speed and attendant laser fluence (LF), on densification behavior, microstructural development, and hardness/wear performance of hard-to-process W-based alloy parts was disclosed.
Abstract: Selective laser melting (SLM) additive manufacturing (AM) of hard-to-process W-based parts with the addition of 2.5 wt.% TiC was performed using a new metallurgical processing mechanism with the complete melting of the high-melting-point powder. The influence of SLM processing parameters, especially laser scan speed and attendant laser fluence (LF), on densification behavior, microstructural development, and hardness/wear performance of SLM-processed W-based alloy parts was disclosed. The densification response of SLM-processed W-based parts decreased both at a low LF of 10.7 J/mm2, caused by the limited SLM working temperature and wetting characteristics of the melt, and at an excessively high LF of 64 J/mm2, caused by the significant melt instability and resultant balling effect and microcracks formation. The laser-induced complete melting/solidification mechanism contributed to the solid solution alloying of Ti and C in W matrix and the development of unique microstructures of SLM-processed W-based alloy parts. As the applied LF increased by lowering laser scan speed, the morphologies of W-based crystals in SLM-processed alloy parts experienced a successive change from the cellular crystal to the cellular dendritic crystal and, finally, to the equiaxed dendritic crystal, due to an elevated constitutional undercooling and a decreased thermal undercooling. The optimally prepared W-based alloy parts by SLM had a nearly full densification rate of 97.8% theoretical density (TD), a considerably high microhardness of 809.9 HV0.3, and a superior wear/tribological performance with a decreased coefficient of friction (COF) of 0.41 and a low wear rate of 5.73 × 10−7 m3/(N m), due to the combined effects of the sufficiently high densification and novel crystal microstructures of SLM-processed W-based alloy parts.
33 citations
TL;DR: In this article, the influence of linear laser energy density on the microstructural evolution and mechanical performance (e.g., densification level, microhardness, wear and tribological properties) of the SLM-processed TiC/AlSi10Mg nanocomposite parts with the novel reinforcing morphology and enhanced mechanical properties by selective laser melting (SLM) additive manufacturing (AM) process was comprehensively studied.
Abstract: The present study has proved the feasibility to produce the bulk-form TiC/AlSi10Mg nanocomposite parts with the novel reinforcing morphology and enhanced mechanical properties by selective laser melting (SLM) additive manufacturing (AM) process. The influence of linear laser energy density (η) on the microstructural evolution and mechanical performance (e.g., densification level, microhardness, wear and tribological properties) of the SLM-processed TiC/AlSi10Mg nanocomposite parts was comprehensively studied, in order to establish an in-depth relationship between SLM process, microstructures, and mechanical performance. It showed that the TiC reinforcement in the SLM-processed TiC/AlSi10Mg nanocomposites experienced an interesting microstructural evolution with the increase of the applied η. At an elevated η above 600 J/m, a novel regularly distributed ring structure of nanoscale TiC reinforcement was tailored in the matrix due to the unique metallurgical behavior of the molten pool induced by the operation of Marangoni flow. The near fully dense TiC/AlSi10Mg nanocomposite parts (>98.5% theoretical density (TD)) with the formation of ring-structured reinforcement demonstrated outstanding mechanical properties. The dimensional accuracy of SLM-processed parts well met the demand of industrial application with the shrinkage rates of 1.24%, 1.50%, and 1.72% in X, Y, and Z directions, respectively, with the increase of η to 800 J/m. A maximum microhardness of 184.7 HV0.1 was obtained for SLM-processed TiC/AlSi10Mg nanocomposites, showing more than 20% enhancement as compared with SLM-processed unreinforced AlSi10Mg part. The high densification response combined with novel reinforcement of SLM-processed TiC/AlSi10Mg nanocomposite parts also led to the considerably low coefficient of friction (COF) of 0.28 and wear rate of 2.73 × 10−5 mm3 · N−1 · m−1. The present work accordingly provides a fundamental understanding of the tailored forming of lightweight multiple nanocomposite materials system by laser AM.
15 citations
TL;DR: A hierarchical linear model with level-2 variance heterogeneity is proposed to model the relationship between ultrasonic attenuation profiles, ultrasonic frequency, and the microstructural parameters of the nanocomposites.
Abstract: In this paper, we propose to use the multiple ultrasonic attenuation profiles measured at different locations of a specimen to infer the microstructure of metal-matrix nanocomposites. We present a general framework to connect the profile data with both explanatory variables and product quality parameters for quality inference. In particular, a hierarchical linear model with level-2 variance heterogeneity is proposed to model the relationship between ultrasonic attenuation profiles, ultrasonic frequency, and the microstructural parameters of the nanocomposites. An integrated Bayesian framework for model estimation, model selection, and inference of the microstructural parameters is proposed through blocked Gibbs sampling, intrinsic Bayes factor, and importance sampling. The effectiveness of the proposed approach is illustrated through case studies.
14 citations
Cites background from "Ultrasonic Attenuation Based Inspec..."
...It may have broad applications where the quality can be sufficiently characterized by multiple profiles....
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TL;DR: In this paper, the correlation between process-induced microstructural features and the material properties including physical and mechanical properties as well as ultrasonic parameters was measured, and it was found that physical properties including densification and physical dimensional changes were closely associated with the morphology and particle size of nanocomposite powders.
14 citations
References
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TL;DR: In this article, the authors describe the physical fundamentals of ultrasonics and materials up to the most sophisticated methods for nondestructive testing of solid material using ultrasonic waves for defects such as cavities, nonbonding, and strength variations.
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1,017 citations
25 Aug 2004-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, the ultrasonic fabrication of bulk lightweight MMNCs with reproducible microstructures and superior properties by use of ultrasonic nonlinear effects, namely transient cavitation and acoustic streaming, to achieve uniform dispersion of nano-sized SiC particles in molten aluminum alloy A356.
Abstract: Lightweight metal matrix nano-composites (MMNCs) (metal matrix with nano-sized ceramic particles) can be of significance for automobile, aerospace and numerous other applications. It would be advantageous to produce low-cost as-cast bulk lightweight components of MMNCs. However, it is extremely difficult to disperse nano-sized ceramic particles uniformly in molten metal. This paper presents a new method for an inexpensive fabrication of bulk lightweight MMNCs with reproducible microstructures and superior properties by use of ultrasonic nonlinear effects, namely transient cavitation and acoustic streaming, to achieve uniform dispersion of nano-sized SiC particles in molten aluminum alloy A356. Microstructural study was carried out with an optical microscope, SEM, EDS mapping, and XPS. It validates a good dispersion of nano-sized SiC in metal matrix. It also indicates that partial oxidation of SiC nanopartilces results in the formation of SiO2 in the matrix. Mechanical properties of the as-cast MMNCs have been improved significantly even with a low weight fraction of nano-sized SiC. The ultrasonic fabrication methodology is promising to produce a wide range of other MMNCs.
559 citations
"Ultrasonic Attenuation Based Inspec..." refers background in this paper
...The mechanisms for the formation of continuous network of the eutectic h-Al2Cu phase in the pure A206 and the morphology modification by Al2O3 in A206–Al2O3 nanocomposites are well studied [1,3,8,33]....
[...]
TL;DR: In this article, the authors approximated the suspended particles by spheres and solved the diffraction problem for a fluid sphere in a fluid medium taking into consideration viscosity and thermal conduction.
Abstract: The suspended particles are approximated by spheres and the diffraction problem for a fluid sphere in a fluid medium is solved taking into consideration viscosity and thermal conduction. The results are discussed numerically for water droplets in air and a satisfactory agreement with Knudsen's attenuation measurements in water fog is found.
508 citations
Book•
14 Jun 2013
TL;DR: In this article, the Fourier Transform and Dirac Delta Function are used to measure the properties of an ultrasonic NDE with models, and the Stationary Phase Method (SPM) is used to scale the model-based defect sizing.
Abstract: 1. An Ultrasonic System. 2. Linear Systems and the Fourier Transform. 3. Fundamentals. 4. Propagation of Bulk Waves. 5. Reciprocal Theorem and Other Integral Relations. 6. Reflection and Refraction of Bulk Waves. 7. Propagation of Surface and Plate Waves. 8. Ultrasonic Transducer Radiation. 9. Materials Attenuation and Efficiency Factors. 10. Flaw Scattering. 11. Transducer Reception Process. 12. Ultrasonic Measurement Models. 13. Near-Field Measurement Models. 14. Quantitative Ultrasonic NDE with Models. 15. Model-Based Flaw Sizing. Appendixes: A. Fourier Transform. B. Dirac Delta Function. C. Basic Notations and Concepts. D. Hilbert Transform. E. Stationary Phase Method. F. Properties of Ellipsoids. Index.
314 citations