Laser Additive Manufacturing of Novel Aluminum Based Nanocomposite Parts: Tailored Forming of Multiple Materials

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 (g) 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 SLMprocessed TiC/AlSi10Mg nanocomposites experienced an interesting microstructural evolution with the increase of the applied g. At an elevated g 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 SLMprocessed 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 g to 800 J/m. A maximum microhardness of 184.7 HV 0.1 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 Â 10 À5 mm 3 Á N À1 Á m À1 . The present work accordingly provides a fundamental understanding of the tailored forming of lightweight multiple nanocomposite materials system by laser AM.

Characterization of Composite Powder Feedstock from Powder Bed Fusion Additive Manufacturing Perspective

“…Since the feedstock of MMCs is not commercially available for AM processing [29], several techniques have been employed in recent years to prepare these powders. The mechanical routes such as regular mixing [30,31,32] and ball milling [33,34,35,36,37,38,39], and non-mechanical methods including gas atomization of a pre-alloyed system [40,41], agent-assisted deposition [42,43] and electrodeposition [44,45] are among these methods. Compared to the mechanical mixing routes, which have attracted a great deal of attention in recent years, the non-mechanical methods have been rarely adopted to prepare composite powder feedstocks for AM purposes.…”

“…The laser absorptivity influences the heat absorption, and the melt pool size [44,47,48], while the flowability and the apparent packing density of the powder play crucial roles in layer thickness (dimensional accuracy) and density of the final part [17,49,50,51,52]. A literature review of the AM processing of MMCs reveals that the mixing of powders, in most cases, has been performed to achieve a distribution of free (non-attached) guest particles throughout the mixed powder system [30,31,32,33,34,35,36,37,38,39,53,54,55]. On the other hand, preserving the spherical shape of metallic powder particles has been considered in some of these studies [36,53,55,56].…”

The Effect of Nanostructures in Aluminum Alloys Processed Using Additive Manufacturing on Microstructural Evolution and Mechanical Performance Behavior

“…As a result, great care is required in the preparation of the feedstock materials and consideration as to what method to fabricate the nanostructure modified feedstock powder is mandatory. Mechanical alloying via ball milling [39,77] has been adopted in many studies for the preparation of the modified powder; however, with this method, there is the potential for the matrix alloy powder to be damaged or become irregular in shape [50]. It is clear that there is a need for better methods to prepare the feedstock material that does not damage the matrix alloy particles.…”