given substrate and thereby enhance the ability of the coating to remain protective particularly after 750 u00b0 c for 825 hours the present disclosure therefore relates to coatings that may be described as having the following formula fe u2014 xcr u2014 yni zal wherein x indicates a level of cr of 20 weight percent to 30 weight percent y indicates a level of ni of 30 weight percent to 50 weight percent and z indicates a level of al of 0 weight percent to 10 weight percent wherein fe accounts for the remainder in addition as will be discussed more fully below such coating compositions may be configured to provide a selected type of diffusion resistant coating which may then restrict the diffusion of elements as between the coating and a given substrate more specifically the alloys may now be configured such that the diffusion resistant coating that is formed may be described as a diffusion barrier coating that may be greater than or equal to 90 0 mole percent of a face centered cubic fcc or gamma u03b3 phase for example 90 0 mole percent to 100 percent of a face centered fcc or gamma u03b3 phase such fcc phase may be characterized as again having a cubic unit cell in the space group number 225 wherein the values of a 1 and a 2 are about 0 36 nm and the value of a 3 is also about 0 36 nm accordingly the aforementioned values may vary u00b1 0 05 nm see fig7 reference herein to space group numbers may be understood as reference to the feature that each space group has a unique number associated with it and the space group numbers by convention are number from.