Excellent Mechanical Properties and Strengthening Mechanism of Fecral 6 Wt.% Al1.8crcufeni2 Alloy Fabricated by Spark Plasma Sintering

The strengthening mechanism of FeCrAl 6 wt.% Al1.8CrCuFeNi2 alloy is investigated using SEM, TEM, XRD and theoretical strengthening models. The XRD pattern shows that the high energy ball-milling leads to the formation of a large number of dislocations in the matrix alloy, and the interplanar spacing changes and characteristic peak position shifts with the increase of strain for FeCrAl 6 wt.% Al1.8CrCuFeNi2. SEM and TEM demonstrated that with the addition of Al1.8CrCuFeNi2 particles into the FeCrAl, there are three different structures in FeCrAl 6 wt.% Al1.8CrCuFeNi2 alloy, the white matrix, the coarse grey Al1.8CrCuFeNi2 particles and the tiny bright white Al2O3 phase, respectively. The tiny Al2O3 phase can inhibit dislocation movement and hinder grain boundary growth by pinning effect, thus lead to enhance the mechanical properties at RT and 800°C. The results of mechanical properties shows that the tensile strength and percentage elongation reached up to 1445MPa, 6.5% at RT. Surprisingly, FeCrAl 6 wt.% Al1.8CrCuFeNi2 alloy shows a high temperature strength about 196MPa and still maintains percentage elongation about 16.6% at 800°C. The calculated value of the square root of sum of squares strengthening model is suitable well with the result of measured data of yield strength for FeCrAl 6 wt.% Al1.8CrCuFeNi2 alloy. It indicated that the excellent mechanical properties are attributed to solid solution strengthening stemmed from the material itself, dislocation strengthening originated from thermal stress during cooling, grain boundary strengthening by high energy ball milling and dispersion strengthening of Al1.8CrCuFeNi2 particles and Al2O3 phase for this work