Deformation hardening and temperature dependence of mechanical properties in ternary ordered alloys based on Ni₃Fe I

Abstract

The variation of hardening factor and resistance to deformation with the quenching and testing temperatures for ordered alloys based on Ni₃Fe was investigated. It was shown that the yield point σ_0.2 and flow stresses are independent of the quenching temperature right up to about 450 ° C. At higher quenching temperatures there are increases in σ_0.2 and in the flow stresses corresponding to small degrees of deformation (ɛ < 10%); the highest mechanical properties are found when the quenching temperature is near the Curie point. In quenching from a temperature above the Curie point the mechanical properties and hardening factor fall suddenly to values corresponding to the disordered state of the alloys. The temperature variation of σ_0.2 is similar to that mentioned above. The deformation stress at high β values and the hardening factor decrease with increase in testing temperature, and below the Curie point they reach values corresponding to the disordered state. The temperature variation of mechanical properties for specimens in which the formation of long-range order is suppressed by special treatment is characterized by the absence of substantial change near the Curie point. The results obtained are discussed in relation to modern dislocation theories of hardening of alloys with long-range order.