Additive Manufacturing: Nano/Micro-mechanics and Length-scale Phenomena: Poster Session
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS: Additive Manufacturing Committee, TMS: Nanomechanical Materials Behavior Committee
Program Organizers: Meysam Haghshenas, University of Toledo; Robert Lancaster, Swansea University; Andrew Birnbaum, US Naval Research Laboratory; Jordan Weaver, National Institute of Standards and Technology; Aeriel Murphy-Leonard, Ohio State University

Tuesday 5:30 PM
March 1, 2022
Room: Exhibit Hall C
Location: Anaheim Convention Center

Session Chair: Meysam Haghshenas, University of Toledo

J-38: A Small Punch Test Study of Additively Manufactured AlSi10Mg: Ziv Ungarish1; Matan Tubul1; Tal Yehuda1; 1Nuclear Research Center Negev
     A small punch test (SPT) investigation of additively manufactured (AM) AlSi10Mg was performed using small disc samples (about 200Ám thickness and 3mm diameter). Effects of different aspects unique to AM materials and SPT were investigated and analyzed, such as microstructure, sample thickness and sample direction. The microstructures and bulk mechanical properties following different heat treatments were characterized using microscopy methods and tensile tests. SPT samples were then prepared from the bulk material. For comparison, 6xxx aluminum alloy samples were also tested by SPT.The results show that the unique AM microstructure does have an effect on the measured mechanical properties when using small samples, compared to bulk samples. Aspects that normally do not require attention when testing wrought aluminum alloys do need to be taken into account when performing SPT on AM aluminum. This conclusion and the effects of the different parameters investigated will be discussed in the presentation.

J-39: Crack-free Three-dimensional Electrical Interconnects 3D Printed on Soft PDMS Substrates: Jacob Brenneman1; Derya Tansel1; Gary Fedder1; Rahul Panat1; 1Carnegie Mellon University
    Nanoparticle 3D printing and sintering is a promising method to achieve freeform interconnects on compliant substrates. Previous strategies to sinter metallic nanoparticles while preserving the soft polymer substrate are rife with problems such as cracking and low conductivity of the metallic features. Capillary force between nanoparticles developed through rapid solvent evaporation in the colloidal ink is hypothesized to initiate cracking during drying. An experimental step-wise variation of the thermal/atmospheric process conditions supports this hypothesis and shows that the presence of air during a low temperature drying step reduces the capillary stress to produce crack-free interconnects with high conductivities (up to 56% of bulk metal) while having an excellent compatibility with the underlying polymer materials. This result is then used to realize interconnects fully-encapsulated by a soft polymer with three-dimensional pillar architectures providing external connections through the polymer, thus also solving an important ‘last-mile’ problem in the packaging of stretchable electronics.

J-41: Effects of Processing Parameters on Residual Stresses in Commercially Pure Ti: Claire Adams1; Kellen Traxel1; Amit Bandyopadhyay1; David Field1; 1Washington State University
     Additive manufacturing can be used to develop desired microstructures for specific mechanical performance. To reduce variance in properties and quality standardization of processing is required. Understanding microstructure and its relation to mechanical properties during thermal processing can improve the use of AM. This research advances development and standardization of the AM process, specifically for titanium, and investigates the link between processing, structure, and properties.Commercially pure titanium samples were printed with Directed Energy Deposition, where parameters such as tool path and energy density were varied. The main goal was to identify how processing steps result in residual stresses in a printed material and relate these effects to microstructure, and study the influence of microstructure on mechanical properties. Microstructural differences were observed using nano-indentation, electron microscopy, and electron backscatter diffraction.

J-42: Investigating Microstructural Features of 304L Stainless Steel Friction-stir Weld with Indentation Methods: Michael Maughan1; Nicolene van Rooyen1; Madhumanti Bhattacharyya1; Indrajit Charit1; 1University of Idaho
    Indentation investigations were conducted on a 304L stainless steel friction-stir weld to understand the effect that microstructural features have on the hardness and property variation within the weld and to measure the size of the microstructural zones with a quantitative technique. Microhardness has traditionally been used for this purpose. In this work, both microindentation and nanoindentation hardness profiles were constructed on a transverse section across the weld and were correlated by extrapolating the nanoindentation hardness to deeper depths. The extrapolated hardness determined by nanoindentation closely reflects the microhardness values throughout the weld. It was found that larger grain sizes increase the nanoindentation modulus variability and texture changes can be detected by quantifying this variability. Nanoindentation was also found to give better sensitivity to weld-zone width measurements and is preferred over microhardness mapping for typical friction-stir welds.

J-43: Microstructure Characterization of As-sprayed and Post-processed Cold-spray Materials: Ryan Cochran1; Shiraz Mujahid1; Yubraj Paudel1; Kyle Considine1; Hongjoo Rhee1; 1Center for Advanced Vehicular Systems at Mississippi State University
    In the cold-spray method, a powdered feedstock is deposited onto a substrate through a pressurized nozzle at a supersonic velocity. During the process, significant microstructural and compositional variations occur, particularly at the interface, owing to small powder particle size and shallow surface penetration compared to particle size. As a result, the mechanical properties of cold-sprayed components generally differ from bulk material, and applications for cold-sprayed products are limited. This study aimed to characterize the microstructures of as-sprayed and post-processed cold-spray samples and quantify mechanical properties. The resultant information and literature data were used to identify microscopic phenomena that show relationships between local particle adhesion, material porosity, and bulk material properties. Experimental results garnered in this study will be incorporated into crystal plasticity modeling for relevant components.

J-44: Probing the Mechanism of Healing Micropores in Additive Manufacturing Al-Li Alloys Using High Resolution X-ray Computed Tomography: Junsheng Wang1; Chenpeng Xue1; 1Beijing Institute of Technology
    Porosity is one of the major obstacles for wide application of wired arc additive manufacturing of Al-Li alloys because it reduces the fatigue life and static properties significantly. Here we found the long chains of porosity along the melt pool can be healed by external forces but the healing cannot be achieved if local strain and pore size was not correlated. Using high resolution X-ray Computed Tomography, we probe the mechanism of this healing process and uncover the effects of porosity and nano precipitates on the mechanical strength, enabling subsequent process optimization for high performance AM components.

J-45: The Effect of Extrusion and Aging on the Mechanical Properties of Additively Manufactured AlSi10Mg : Adi Benartzy1; Gal Hadad1; Arie Bussiba2; Moshe Nahmany2; 1Ben Gurion University; 2N.R.C.N
    Additive manufacturing is use to build three-dimensional parts, from a CAD model. The parts are constructed, layer by layer from powder, and selectively melted by laser or electron beam in the powder bed fusion process. This method enables the production of complex geometries of versatile materials parts. In this study, powder laser bed fusion technique was used to make AlSi10Mg extrusion billets. The AM billets were subjected to stress relief Heat Treatment (HT) and hot extrusion process. The mechanical properties and microstructure of the extruded AM billets and aged hardened were evaluated. A significant improvement of the extruded samples mechanical properties was found in comparison to cast and as-built material. In some cases, the yield stresses, tensile stresses and elongation were found to increase by 30-40%. Manufacturing of extrusion billets by additive manufacturing can be consider as means to gain better mechanical properties of final heavy-duty products by extrusion.