Effect of Solid Solution Treatment on Microstructure of Fe-Ni Based High Strength Low Thermal Expansion Alloy

Effect of aging on microstructures and properties of Mo-alloyed Fe–36Ni invar alloy

“…This result suggests that the Mo alloying plays an important role in enhancing strength of the invar alloy. Solution treatment at 1050°C results in a decrease in strength, this phenomenon should be related to the dissolution of the primary carbides into the austenite matrix during heating [10]. Aging at 525°C produces an apparent increase in strength, and the sample aged for 3 h exhibits the highest strength of 827 MPa.…”

“…Some residual precipitates, indicated by arrows in Fig. 6a, are observed in the matrix, probably due to the incomplete dissolution of the Mo 2 C particles during heating [10]. However, three kinds of the Mo 2 C particles with the size of 50-170 nm, 150-390 nm and 350-500 nm, respectively, are observed in austenite interior as shown in Fig.…”

“…Conventional strengthening methods, such as solid-solution strengthening [10], grain refinement [5], work hardening [8,11] and precipitation hardening [12][13][14][15][16], have been developed in invar alloys, e.g. Fe-36Ni [5,11], Fe-Ni-Co [12,17,18], Fe-Ni-Ti [19] and Fe-Ni-Mo [10,16], etc.…”

“…Fe-36Ni [5,11], Fe-Ni-Co [12,17,18], Fe-Ni-Ti [19] and Fe-Ni-Mo [10,16], etc. Vinogradov et al [5] reported that the tensile strength of the base Fe-36Ni alloy can be increased up to 912 MPa when its mean grain size was refined to 0.18 μm by the equal-channel angular pressing (ECAP).…”

“…Meanwhile, this alloy shows a low CTE value of 3 Â 10 À 6 /°C in the temperature range of 30-150°C. Zhang et al [10] and Lu et al [16] studied the effect of solid-solution treatment and carbide precipitates on mechanical properties of the Fe-Ni-Mo-C and Fe-Ni-Mo-V-C invar alloys, respectively. However, little information on size, morphology and distribution of the precipitates during aging was reported.…”