PSI - Issue 69

Alberto Coda et al. / Procedia Structural Integrity 69 (2025) 26–34

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Ni3Ta-X alloys were melted in a materials (Figure 2). EDM cut as-cast condition and after thermal 1200°C and 1350°C for 1 and 4

vacuum arc furnace from pure raw samples of ingots were analyzed in treatments (TT) under vacuum at

hours, respectively.

Figure 2 Vacuum arc melted Ni 3 Ta-X alloys. Five different compositions were prepared: The first alloy chemistry was composed of binary Ni-Ta with the ratio 3:1 to form the intermetallic Ni 3 Ta. The other investigated chemistries consisted of adding 1 at. % of Cu and Co in expense of either Ni or Ta. Prepared chemistries are presented in table 1.

Table 1 Nominal composition of the investigated alloys.

Alloy

Nominal Composition [at. %]

Ni 75 75 74 75 74

Ta 25 24 25 24 25

Cu

Co

1 2 3 4 5

1 1

1 1

2.2 Samples characterization Microstructural analysis was performed by optical microscopy and field emission SEM with Backscattered Electrons (BSE) on metallographic cross-sections. Metallographic samples were prepared by standard grinding using SiC papers followed by polishing with 6 µm and 3 µm colloidal silica suspension, and final washing in ultrasound bath for 10 minutes. Microhardness (HV) testing according to PN-EN ISO 6507-1 was done to verify the alloying additions effect on plastic deformation behavior. A square-based diamond pyramid indenter (Vickers) was used. Ten measurements for each sample were performed only on the matrix. Differential Scanning Calorimetry (DSC, TA Instruments DSC100) was finally performed to measure the transformation temperatures of as-cast and thermally treated samples, according to the standard procedure ASTM F2004-24.