Resettable alloys and manufacturing method for the same

A method for manufacturing a resettable alloy comprising body-centered tetragonal(BCT)-face-centered cubic(FCC) dual structure and having a composition Fe100-a-b-cMnaCrbCc, wherein 3≤a≤15, 0<b≤11.87, and 0<c≤2.01 wt. %, the body-centered tetragonal(BCT)-face-centered cubic(FCC) dual structure comprising:

• BCT martensite phase matrix;
• and
• FCC austenite phase present within the matrix,
• the method comprising the steps of:
• preparing and melting alloy elements to which segregation engineering is applicable, to afford an alloy;
• applying a two-step heat treatment to the alloy to form a BCT-FCC dual phase microstructure that is able to undergo metastable reversible phase transformation,
• wherein the two-step heat treatment comprises;
• homogenization treatment (H-treatment) conducted at 850-1230° C., for 0.5 to less than 96 hours followed by air cooling as a first step;
• and
• preferential site segregation treatment (P-treatment) conducted for 0.1 to 192 hours followed by quenching as a second step;
• and
• optimizing resettability in the alloy through resetting treatment (R-treatment) conducted for 1 minute to 192 hours,
• wherein the P-treatment and the R-treatment are conducted at a following minimum temperature (Tmin) to a following maximum temperature (Tmax),
• Tmax(° C.)=−18·wt %(Mn)+820
• Tmin(° C.)=−18·wt %(Mn)+640,
• wherein the FCC austenite phase retained within the BCT martensite phase matrix is maintained at a level of 50 vol. % or less after the H-treatment.