Enhancing the High Temperature Tensile Strength of Fe36Ni36Cr10Mo1Al17 Alloy by Substituting Al with Si

By substituting Al with Si element, the Fe₃₆Ni₃₆Cr₁₀Mo₁Al_17−XSi_X (X = 0, 1, 2 and 4) alloys were prepared and their mechanical properties were tested at high temperature ranging from 600 to 800 °C. The yield strength and ultimate tensile strength of the 4 alloys showed a trend of increasing first and then decreasing when tested at 700 °C. All the alloys with Si added showed enhanced strength and elongation compared with the alloy without Si addition. Fe₃₆Ni₃₆Cr₁₀Mo₁Al₁₅Si₂ exhibited the highest yield strength of 516 MPa, ultimate strength of 570 MPa, and elongation of 13.1% at 700 °C. The 2% Si addition increases the ultimate strength by 102 MPa compared with Si0 alloy (468 MPa), which is attributed to the strengthened boundaries with addition of Si element. Moreover, the yield strength and ultimate strength of the Fe₃₆Ni₃₆Cr₁₀Mo₁Al₁₅Si₂ alloy represented a decreasing trend while elongation showed an increasing trend as temperature increased from 600 to 800 °C. The rapid reduction of the strength and increase of the elongation was originated from the rapid softening of the B2 phase at 800 °C compared with that of FCC phase.

Graphical abstract