Use of High Magnetic Field to Control Microstructural Evolution in Metallic and Magnetic Materials

Ludtka, G.M. ; Mackiewicz- Ludtka, G. ; Wilgen, J.B. ; Kisner, R.A.

关键词: CURIE POINT;    DEFORMATION;    EVALUATION;    GRAIN SIZE;    MAGNESIUM ALLOYS;    MAGNETIC FIELDS;    MAGNETIC MATERIALS;    MICROSTRUCTURE;    MONITORING;    PEARLITE;    PHASE TRANSFORMATIONS;    PHYSICS;    PREC;   

DOI  :  10.2172/982755
RP-ID  :  ORNL/NFE-06-00414, Amendment 1
PID  :  OSTI ID: 982755
Others  :  TRN: US201015%%1002

美国|英语

来源: SciTech Connect

【 摘 要 】

The Amendment 1, referred to as Phase 2, to the original CRADA NFE-06-00414 added tasks 3 through 7 to the original statement of work that had two main tasks that were successfully accomplished in Phase 1 of this project. In this Phase 2 CRADA extension, extensive research and development activities were conducted using high magnetic field processing effects for the purpose of manipulating microstructure in the SAE 5160 steel to refine grain size isothermally and to develop nanocrystalline spacing pearlite during continuous cooling, and to enhance the formability/forgability of the non-ferrous precipitation hardening magnesium alloy AZ90 by applying a high magnetic field during deformation processing to investigate potential magnetoplasticity in this material. Significant experimental issues (especially non-isothermal conditions evolving upon insertion of an isothermal sample in the high magnetic field) were encountered in the isothermal phase transformation reversal experiments (Task 4) that later were determined to be due to various condensed matter physics phenomenon such as the magnetocaloric (MCE) effect that occurs in the vicinity of a materials Curie temperature. Similarly the experimental deformation rig had components for monitoring deformation/strain (Task 3) that were susceptible to the high magnetic field of the ORNL Thermomagnetic Processing facility 9-T superconducting magnet that caused electronic components to fail or record erroneous (very noisy) signals. Limited experiments on developing nanocrystalline spacing pearlite were not sufficient to elucidate the impact of high magnetic field processing on the final pearlite spacing since significant statistical evaluation of many pearlite colonies would need to be done to be conclusive. Since extensive effort was devoted to resolving issues for Tasks 3 and 7, only results for these focused activities are included in this final CRADA report along with those for Task 7 (described in the Objectives Section of this report).