| The thermal expansion and the high temperature deformation behaviors have been studied in the composition range of 0-50% Ni for Fe-Ni binary alloys. With increasing Ni content, the α-γ transformation temperature decreases and the thermal expansion coefficients of α and γ phases decrease above 10% Ni. The thermal expansion coefficients of Fe-Ni alloys with Ni content lower than 30% Ni or greater than 40% Ni are about 10^(-5) but chat of 36% Ni alloy is smaller than 10^(-6). The composition showing the lowest thermal expansion coefficient was dependent on the tested temperature range, and the compositions are 36%, 45% and 27.5% Ni in the temperature range of RT-50℃, 50-200℃ and 200-500℃, respectively. With increasing Ni content the compressive true peak stress and its true peak strain at 1000℃ are increased. The yield stress and the compressive peak stress at 1000℃ reached to the high stresses at 25-30% Ni after a steep .increase at about 20% Ni, and then slightly decreased to 36% Ni. The relation between the true stress and the true strain in the compression test at 1000℃ was of the typical power expression type(σ=Kεⁿ) in the strain hardening region. The strength coefficient and the strain hardening coefficient in 20% Ni are estimated 8㎏/㎟ and 0.29 as the highest values while the coefficients in 36% Ni are 4.62 ㎏/㎟ and 0.1 as the lowest values, respectively. |
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