Paradigm Shift in Materials Processing - The Intelligent Processing Revolution

During the last several decades, the importance of materials processing in the control of microstructure and materials properties has been recognized and, accordingly, the materials engineering community has dedicated much effort to studying the physics of the process. These endeavors have provided an understanding of the phenomena which are relevant. However, a paradigm shift is taking place in that the physics oriented approach to materials processing is being replaced by a control oriented approach. What is needed today is the ability to control the process and, thus, the trajectory of the controllable variables in a temporal space. Such a knowledge based approach to materials processing which requires understanding, sensors, and controls is the revolution taking place in the materials engineering field. The essence is a process which can learn and develop \u27\u27intelligence\u27\u27 as it progresses. This address will present and discuss the basis and the need for a knowledge based approach to materials processing. Furthermore, specific industrial examples will be given to illustrate implementation of intelligent processing. Finally, the challenges ahead and the impediments we face as a community will also be addressed

Resonant Oscillation of a Liquid Metal Column Driven by Electromagnetic Lorentz Force Sources

In this paper, a theoretical study is conducted in order to establish the feasibility of a liquid metal acoustic resonator (liquid gallium or liquid aluminum) for high-amplitude acoustic oscillations. The fundamental resonant frequency typically lies between 5 and 40 kHz. The oscillations are induced by an alternating Lorentz force density applied directly to the liquid metal volume. Depending on the boundary conditions, two different resonator types (open-closed and open-open) are theoretically investigated. The analysis incorporates the effects of impedance termination, volume absorption, wall friction, acoustic radiation from the open end, and nonlinear inflow-outflow losses. The actual elasticity of the container, either a ceramic or quartz tube, and the coupled solid-liquid interactions are taken into consideration. Based on this investigation, theoretical predictions are conducted for the quality factor and the pressure level for the liquid metal resonator under various geometric and boundary conditions. They indicate that resonant amplitudes of 10-20 arm can be achieved using commercially available high-current audio amplifiers

Energy Saving Melting and Revert Reduction Technology: Innovative Semi-Solid Metal (SSM) Processing

Semi-solid metal (SSM) processing has emerged as an attractive method for near-net-shape manufacturing due to the distinct advantages it holds over conventional near-net-shape forming technologies. These advantages include lower cycle time, increased die life, reduced porosity, reduced solidification shrinkage, improved mechanical properties, etc. SSM processing techniques can not only produce the complex dimensional details (e.g. thin-walled sections) associated with conventional high-pressure die castings, but also can produce high integrity castings currently attainable only with squeeze and low-pressure permanent mold casting processes. There are two primary semi-solid processing routes, (a) thixocasting and (b) rheocasting. In the thixocasting route, one starts from a non-dendritic solid precursor material that is specially prepared by a primary aluminum manufacturer, using continuous casting methods. Upon reheating this material into the mushy (a.k.a. "two-phase") zone, a thixotropic slurry is formed, which becomes the feed for the casting operation. In the rheocasting route (a.k.a. "slurry-on-demand" or "SoD"), one starts from the liquid state, and the thixotropic slurry is formed directly from the melt via careful thermal management of the system; the slurry is subsequently fed into the die cavity. Of these two routes, rheocasting is favored in that there is no premium added to the billet cost, and the scrap recycling issues are alleviated. The CRP (Trade Marked) is a process where the molten metal flows through a reactor prior to casting. The role of the reactor is to ensure that copious nucleation takes place and that the nuclei are well distributed throughout the system prior to entering the casting cavity. The CRP (Trade Marked) has been successfully applied in hyper-eutectic Al-Si alloys (i.e., 390 alloy) where two liquids of equal or different compositions and temperatures are mixed in the reactor and creating a SSM slurry. The process has been mostly used for hypo-eutectic Al-Si alloys (i.e., 356, 357, etc.) where a single melt passes through the reactor. In addition, the CRP (Trade Marked) was designed to be flexible for thixocasting or rheocasting applications as well as batch or continuous casting. Variable heat extraction rates can be obtained by controlling either the superheat of the melt, the temperature of the channel system, or the temperature of the reactor. This program had four main objectives all of which were focused on a mechanistic understanding of the process in order to be able to scale it up, to develop it into a robust process,and for SSM processing to be commercially used