Positive Deviation of the Hall-Petch Relationship for Aluminum Condensates Alloyed with Iron

Abstract

The structure and strength properties of vacuum aluminum condensates alloyed with iron in the concentration range of 0.1 – 3.2 at. % is studied in the paper. It is shown that up to a concentration of about 2 at. % Fe, the grain size decreases, the strength properties increase and the lattice parameter values of these objects remain unchanged. It is found that at an iron concentration of up to ~ 2 at. % its atoms are concentrated in the grain boundaries of the aluminum matrix metal in the form of grain boundary segregation. At high concentrations, the structure of condensates is a supersaturated solution of iron in the FCC crystal lattice of aluminum. Highly dispersed Al13Fe4 intermetallic compounds are present at the grain boundaries and within the volume of grains. It has been found that the Hall-Petch coefficient for one-component aluminum condensates is 0.04 MPa·m1/2, which is typical for this metal. For Al-Fe condensates, a positive deviation from the Hall-Petch dependence is observed and the coefficient k increases to 0.4 MPa·m1/2 for a structure with grain boundary segregations and to 0.14 MPa·m1/2 for condensates containing intermetallic compounds. The obtained experimental results are explained by the different structural-phase state of the grain boundaries of the aluminum matrix.

Keywords

• grain boundary segregation
• vacuum condensate
• intermetallic compound
• al-fe
• grain size