Materials Design and Processing Optimization for Advanced Manufacturing: From Fundamentals to Application: Materials Design and Processing Optimization: Session V
Sponsored by: TMS Structural Materials Division, TMS: Alloy Phases Committee
Program Organizers: Wei Xiong, University of Pittsburgh; Dana Frankel, Apple Inc; Gregory Olson, Massachusetts Institute of Technology
Wednesday 8:30 AM
March 2, 2022
Room: 253B
Location: Anaheim Convention Center
Session Chair: Le Zhou, Marquette University; Hanlei Zhang, University of Pittsburgh
8:30 AM Invited
FeNiMnAl(Cr) and FeCoMnAl Multi-principal Component Alloys: Ian Baker1; 1Dartmouth College
In the 1970’s, Strutt and Polvani showed that a semi-coherent B2/L21 NiAl-Ni2AlTi alloy had superior creep properties compared to Ni-based superalloys. Based on these observations, we embarked in 2004 on developing high-strength two-phase multi-principal component alloys (MPCAs) based on FeNiMnAl and FeCoMnAl. Four different microstructures were produced in FeNiMnAl MPCAs: 1) ultrafine (5-50 nm) B2/L21 or b.c.c./B2 <100>-aligned microstructures in near-equiatomic FeNiMnAl; 2) fine (50-70 nm) f.c.c./B2 eutectoid microstructures in Ni and Al-lean MPCAs; 3) coarser (0.5-1.5 µm) f.c.c./B2 lamellar eutectic microstructures in MPCAs with ≤15 at.% Al; and 4) single-phase MPCAs such as Fe40.4Ni11.3Mn34.8Al7.5Cr6. These alloys could be strong (yield strength ~2350 MPa), or ductile (>50% elongation), but not both. FeCoMnAl MPCAs, which were B2, B2/f.c.c., B2/h.c.p. or B2/L21, were very hard and brittle but some showed excellent soft magnetic properties and high stability to ~873 K. The microstructures and the resulting mechanical and magnetic properties are described.
8:55 AM
An Experience in Development of Modified Invar Alloy: Building the Capacity of Overhead Power Transmission Lines: Ashmita Patra1; Narahari Satyanarayana1; Gayatri Yadav1; 1Mishra Dhatu Nigam Ltd
Growing electricity consumption demands multifunctional alloy core in an electrical conductor, doubling the transmission capacity of overhead high voltage lines. Replacement of high strength steel core by modified invar is a thrust area of research to prevent sagging without extra infrastructure construction. Standard invar has high sag resistance due to its very low coefficient of thermal expansion (CTE) (1.1x10-6 upto 200°C) but limited in tensile strength of 800MPa in 90% cold worked condition. Chemistry of standard invar is modified to increase Curie temperature to 240°C and simultaneously strengthen by FCC vanadium carbide precipitation and cold work to obtain 1300MPa tensile strength without impairing ductility and low CTE characteristics. Stoichiometric V/C ratio avoid excess dissolution of carbon or vanadium in the matrix which deteriorates CTE. Aging after optimised % cold reduction promotes coherent precipitate distribution, facilitating strengthening upon further cold working. Fe-Ni-Co-V-C-Cr alloy under present study has achieved UTS>1300MPa keeping CTE<1.8X10-6.
9:15 AM
Predicting the Columnar-to-equiaxed Transition during Additive Manufacturing of Concentrated Multicomponent Alloys: Christopher Hareland1; Gildas Guillemot2; Oriane Senninger2; Charles-André Gandin2; Peter Voorhees1; 1Northwestern University; 2CEMEF - Centre de Mise en Forme des Matériaux
The solidification structures that form during processing dictate the properties of additively manufactured (AM) components. For example, the columnar-to-equiaxed transition (CET), describes a shift from columnar to equiaxed grains, which improves resistance to hot-tearing during processing and the final mechanical properties of the component. Existing analytical models of the CET are limited by dilute-solution models of dendritic growth that poorly describe the behavior of concentrated multicomponent alloys. Here, we use a dissipation relation incorporating solute drag to determine the interfacial response functions and find that the partition coefficient depends on the degree of drag in the system. This result is used in an interfacial stability analysis to determine the tip radius for dendritic solidification. With CALPHAD free energies, this model of dendritic growth can be used within a CET model to improve calculations of the processing conditions required to observe the CET during the AM of modern, technologically relevant alloys.
9:35 AM Invited
NOW ON DEMAND ONLY: Characterization of the Microstructure and Deformation Substructure
evolution in Additively Manufactured High-entropy Alloys via Correlative EBSD and ECCI
: Zhangwei Wang1; Ji Gu1; Lin Guo1; Yong Liu1; Min Song1; 1Central South University
We investigate the microstructure and deformation substructure evolution in an additively manufactured N-doped FeCoNiCr high-entropy alloy (HEA) by means of a scanning electron microscopy (SEM)-based approach, which involves correlative electron channeling contrast imaging (ECCI) and electron backscatter diffraction (EBSD) techniques. The combinational use of EBSD and ECCI reveals the microstructure of the additively manufactured HEA across various length scales, including a bimodal grain structure, low angle boundaries, and dislocation networks, along with the quantitative evolution of geometrically necessary dislocations (GNDs) distribution. The deformation microstructure evolution of the HEA upon loading is uncovered to clarify the strain hardening mechanism. The present approach shows comparable resolution to traditional bright field transmission electron microscopy (TEM) imaging, yet with far higher efficiency and affordability.