*Magnesium Containing High Entropy Alloys DOI: http://dx.doi.org/10.5772/intechopen.98557*

diffusion is not entirely common for every HEA. Depending upon the alloy composition, the behavior varies [9]. The diffusion studies have been conducted in a limited number of alloys. Earlier studies on CoCrFeMnNi at near *Tm* temperatures exhibit sluggish diffusion as per diffusion couple method and quasi binary path [10, 11]. A few studies suggest that the diffusion is not sluggish in CoCrFeMnNi within 1073K-1373K temperature range, when analyzed with Radiotracer method using <sup>63</sup>*Ni*. Bulk diffusion is the prominent mode of diffusion in a single crystal CoCrFeMnNi, while bulk diffusion is also in polycrystalline alloys at high temperatures [9]. Using Boltzman-Matano method to study diffusion behaviour also reveals similar results [12]. Radiotracer method using <sup>51</sup>*Cr*, <sup>54</sup>*Mn*, <sup>57</sup>*Cr*, <sup>59</sup>*Fe* and <sup>63</sup>*Ni* in the same alloy also produced similar non-sluggish diffusion behaviour when analyzed at a temperature range of 1073K-1373K [13–17]. AlCoCrFeNi HEAs exhibit sluggish diffusion behaviour when analyzed using diffusion couple method [18]. Numerical assessments also suggest similar behaviour. Another study on *AlxCoCrCuFeNi* where x=1, 1.5, 1.8 suggests that the diffusion retards with increasing the Alconcentration [19].
