The Influence of Cr Addition on the Microstructural and Corrosion Properties of Cr-Fe-Mn Alloys
Open Access
- Author:
- Blanchard, Cameron Francis
- Area of Honors:
- Materials Science and Engineering
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Hojong Kim, Thesis Supervisor
Robert Allen Kimel, Thesis Honors Advisor - Keywords:
- X-ray Diffraction
Vickers Hardness
Optical Microscopy
Materials Science
Corrosion
Electrochemical Polarization - Abstract:
- The influence of chromium addition on the microstructural and corrosion properties of Cr-Fe-Mn alloys was investigated using polarization measurements, Vickers hardness tests, x-ray diffraction, and optical microscopy. Electrochemical polarization measurements of Cr-Fe-Mn specimens as a function of Cr content, from 0-25 at% Cr, were performed in deaerated 1 M sodium chloride and deaerated 1 M sodium sulfate electrolytes. The results indicate that corrosion resistance increased as Cr content increased. In addition, using optical microscopy, corrosion due to active dissolution and pitting was imaged on the alloy surfaces after being subjected to the polarization measurements. Vickers hardness testing and x-ray diffraction were utilized to assess the microstructure of the alloys. Hardness increased from 220 HV to 234.2 HV as the Cr content increased from 0-10 at%, with a peak hardness of 250.9 HV observed at 15 at% Cr. A sharp drop in hardness from 250.9 HV to 209.2 HV was detected at 20 at% Cr, with another decrease in hardness to 203.4 HV at 25 at% Cr. XRD revealed that alloys from 0-10 at% Cr possessed two-phase HCP + FCC behavior, and eventually transitioned to a ternary HCP + FCC + BCC crystal structure at 15 at% Cr. At 20 at% Cr, binary FCC + BCC phases were observed, while a single BCC structure was present at 25 at% Cr.