Application of DSC Method in Studies on Phase Transitions of Ni Superalloys

Abstract

The paper presents results of calorimetric studies of foundry nickel superalloys: IN100, IN713C, Mar-M247 and ŻS6U. Particular attention was paid to determination of phase transitions temperatures during heating and cooling. The samples were heated to a temperature of 1500°C with a rate of 10°C⋅min -1 and then held at this temperature for 5 min. After a complete melting, the samples were cooled with the same rate. Argon with a purity of 99.99% constituted the protective atmosphere. The sample was placed in an alundum crucible with a capacity of 0.45 cm 3 . Temperature and heat calibration was carried out based on the melting point of high-purity Ni. The tests were carried out by the differential scanning calorimetry (DSC) using a Multi HTC high-temperature calorimeter from Setaram. Based on the DSC curves, the following temperatures were determined: solidus and liquidus, dissolution and precipitation of the γ' phase, MC carbides and melting of the γ'/γ eutectic. In the temperature range of 100-1100°C, specific heat capacity of the investigated superalloys was determined. It was found that the IN713C and IN100 alloys exhibit a higher specific heat while compared to the Mar-M247 and ŻS6U alloys.

Measurement of high temperature phase stability and thermophysical properties of alloy 740

“…10. 10,20,21 It is clear from this figure that the C P data obtained for alloy 740 falls within the band of similar data reported for other Ni based alloys with different compositions.…”

“…15 together with the reported for other Ni based superalloys. 10,[19][20][21] Thermal conductivity data obtained in the present study compare well with the Special Metal Corporation data 19 at the low temperature, but it deviates at high temperature. From Fig.…”

“…From Fig. 9, it is clear that the present heat capacity data at low temperature do not match with same calculated by Mills formalism 9 and those reported by 10,20,21 Besides these, the present C P data fall well within the statistical variation of C P data reported for other Ni based superalloys, which is clearly witnessed in Fig. 10.…”

Carbides Formation in MarM247 Directional Solidified during Stress-Rupture Test at High Temperature

“…The casting process of Mar-M247 alloy, which encompasses the solidification temperature range of 1172˚C to 1187˚C, involves constitutional decomposition in the as-cast product, resulting in small eutectic compositions of gamma and gamma prime in the inter-dendritic zones [7]. The processing of nickel-based superalloys includes heat treatment, which entails the dissolution of the "butterfly-shaped" gamma prime phase formed during the cooling of the cast product.…”

Influence of Casting Parameters on Fatigue Properties of the Żs6u-Wi Alloy

“…Nickel-based superalloys are classic materials used in the aerospace industry. Their wide application is related to the possibility of operation at high temperatures, their high creep resistance, fatigue and resistance to aggressive atmosphere [2]. The many advantages of nickel-based alloys show that without these versatile materials, the aerospace industry would have a hard time finding a replacement alloy.…”