Oxide dispersion strengthened nickel based alloys via spark plasma sintering

Abstract

Oxide dispersion strengthened (ODS) nickel based alloys were developed via mechanical milling and spark plasma sintering (SPS) of Ni-20Cr powder with additional dispersion of 1.2 wt.% Y 2 O 3 powder. Furthermore, 5 wt.% Al 2 O 3 was added to Ni-20Cr-1.2Y 2 O 3 to provide composite strengthening in the ODS alloy. The effects of milling times, sintering temperature, and sintering dwell time were investigated on both mechanical properties and microstructural evolution. A high number of annealing twins was observed in the sintered microstructure for all the milling times.However, longer milling time contributed to improved hardness and narrower twin width in the consolidated alloys. Higher sintering temperature led to higher fraction of recrystallized grains, improved density and hardness. Adding 1.2 wt.% Y 2 O 3 to Ni-20Cr matrix significantly reduced the grain size due to dispersion strengthening effect of Y 2 O 3 particles in controlling the grain boundary mobility and recrystallization phenomena. The strengthening mechanisms at room temperature were quantified based on both experimental and analytical calculations with a good agreement. A high compression yield stress obtained at 800 °C for Ni-20Cr-1.2Y 2 O 3 -5Al 2 O 3 alloy was attributed to a combined effect of dispersion and composite strengthening.

On the creep behavior of dual-scale particle strengthened nickel based alloy

“…The average elastic modulus and hardness were measured as approximately 200 GPa and 5.5 GPa, respectively. As reported earlier, Ni-20Cr-1.2Y 2 O 3 -5Al 2 O 3 alloy has better mechanical properties than Ni-20Cr [19]. It can be noted from Fig.…”

“…Gas atomized Ni-20Cr powder with nominal composition Ni-19.6Cr-0.2Fe-0.8Mn-0.9Si (wt.%) and mean particle size of 23.6±1.1 m, Y 2 O 3 powder with high purity (99.99%) and mean particle size of 30-40 nm, and Al 2 O 3 powder with 99.99% purity and mean particle size of 300-400 nm were all acquired from the American Elements Inc. The nominal compositions of Ni-20Cr, Ni-20Cr-1.2Y 2 O 3 and Ni-20Cr-1.2Y 2 O 3 -5Al 2 O 3 alloys were prepared via high energy ball milling using Spex 8000M shaker mixer/mill.Details of ball milling and SPS can be found in an earlier report [19]. The compressive creep experiments were performed at a temperature of 800 o C and a stress of 100 MPausing a 2320 model Applied Test Systemslever arm creep tester (Butler, PA, USA).For Transmission electron microscopy (TEM), a FEITecnai TF30-FEG STwin STEM operated at an accelerating voltage of 200kV was used.…”

Additively manufactured oxide dispersion strengthened nickel-based superalloy with superior high temperature properties

“…Based on Equation (6), the ratio of σ ODS values for LMD-MA and HE-MA can be calculated by division, which indicates that the σ ODS of LMD-MA is nearly 4 times of that for HE-MA. Moreover, the compression strength of LMD-MA under different temperatures is compared with other alloys (Markus et al 2018;Zhang et al 2012;Pasebani et al 2015;Semiatin et al 2001;Shao et al 2019;Tao et al 2019;Zhang et al 2014;Kim et al 2018), as shown in Figure 14. Obviously, LMD-MA exhibits preferable high-temperature performance at elevated temperatures.…”

Effects of Nano-Y2O3 and Sintering Parameters on the Fabrication of PM Duplex and Ferritic Stainless Steels

“…The addition of yttria increases strengthening, inhibits dislocation motion, increases the deformation resistance, controls the recovery and re-crystallization process and inhibits the grain growth [43]. As a result, the yttria-dispersed stainless steel sintered at 1000°C shows maximum yield stress than the yttria-free stainless steels.…”