Dynamic Softening Mechanism of Platinum Thermomechanically Deformed at Low Strain Rate

TL;DR

This study explores how pure platinum softens during deformation at high temperatures and low strain rates.

Contribution

The paper identifies dynamic recovery as the main softening mechanism in platinum during thermal deformation.

Findings

Grain size and dislocation density decrease with increasing deformation temperature.

Dynamic recovery based on dislocation cross-slip/climb is the primary softening mechanism.

Continuous and geometric dynamic recrystallization improve microstructural homogeneity above 650 °C.

Abstract

The mechanical behavior of pure Pt at elevated temperatures is critical for its high-temperature processing and applications. To understand its thermal deformation behavior and reach better processing control, thermal compression deformation was conducted for pure Pt in this work with a strain rate of 0.01 s−1 and temperatures ranging from 500 to 700 °C, followed by microstructure characterization by using electron backscatter diffraction (EBSD) technique. The results indicate that the grain size, fraction of low-angle grain boundaries, and dislocation density are generally reduced with increasing temperature. An analysis combining true stress–strain curves and microstructural characteristics indicates that dynamic recovery based on dislocation cross-slip/climb is always a main softening mechanism of pure Pt during thermal deformation. Continuous dynamic recrystallization and geometric dynamic recrystallization also occur when the deformation temperature exceeds 650 °C, which will effectively improve the microstructural homogeneity of pure Pt.

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