Pan American Materials Congress Plenary: Session III
Program Organizers: Marc Meyers, University of California, San Diego
Wednesday 8:30 AM
March 1, 2017
Room: Marina G
Location: Marriott Marquis Hotel
8:30 AM Plenary
Recent Progress in High Entropy Alloy Research: Zhiqiang Fu1; Benjamin MacDonald1; Baolong Zheng1; Weiping Chen2; Yaojun Lin3; Fei Chen3; Lian Zhang3; Yulia Ivanisenko4; Yizhang Zhou1; Horst Hahn5; Enrique J. Lavernia1; 1University of California, Irvine; 2South China University of Technology; 3Wuhan University of Technology; 4Karlsruhe Institut of Technology; 5Karlsruhe Institute of Technology
High-entropy alloys (HEAs) have emerged as an intellectually rich area of research, partly as a result of their exceptional properties and unusual characteristics. HEAs are defined by their multi-principal-element compositions and have been described in terms of “four core effects”: high entropy, severe lattice distortion, sluggish diffusion, and the cocktail effect. This lecture focuses on fundamental phenomena inherent to HEAs that have been studied since the inception of this novel material class and how our understanding of these phenomena has evolved since. Published results, as well as those obtained by our research group, are highlighted to provide insight on these phenomena and how they affect key scientific issues regarding HEAs, such as phase formation mechanisms, thermal stability, deformation mechanisms and strengthening mechanisms. Persistent challenges regarding HEAs are addressed and experimental approaches to investigate each are described and proposed.
9:10 AM Plenary
High Temperature Solutions through Materials and Processes for Engines under Heavy Thermal Fatigue Conditions: Salvador Valtierra1; 1Nemak
In addition to reducing vehicle weight and lowering fuel consumption and emissions, current research efforts in the automotive industry have been focused on improving the high temperature performance of key engine components, as aluminum Heads and aluminum Engine Blocks, In the present work several solutions for the design engineer for the current demand of high performance engines and the additive effects of casting process, alloys and heat treatment are shared, specifically in relation to preserving the mechanical and fatigue properties of the cast aluminum alloys used in such components at temperatures of 200°C to 300°C under thermal an mechanical fatigue. Considering than in 1950, the VW Beetle with a top speed of 115 km/h for the standard 34 hp engine (1,131 cc.= 30 HP/ L), this 30 to 40 HP/ L of displacement remained almost constant until the year 2000 from 2010 we have engines demanding 130 to 150 HP/L. this condition will have a high demand on the materials used and is of great importance for the casting designer, specifically in relation to preserving the mechanical and fatigue properties of the cast aluminum alloys used in such components at temperatures of 200°C to 300°C under thermal an mechanical fatigue ( low and high cycle fatigue ). The effects of casting process, alloy and heat treatment and microstructural variables such as solidification rate, dendrite arm spacing (DAS), level of porosity, eutectic silicon modification, and Fe-rich intermetallic phases were evaluated. For thermal fatigue, the test method employed to evaluate these materials is called “constrained thermal fatigue”. By thermal cycling between 66 and 288C (150 and 550F) For Mechanical fatigue, high cycle fatigue (HCF) tests, The fatigue tests were performed at 150°C and different stress applied . Fatigue strength was determined on specimens from of 319 and 356 and 354 alloys. Test specimens were obtained from commercial automotive cylinder head castings produced from both semi-permanent mold and precision-sand casting methods and from directionally solidified experimental castings.
9:50 AM Break