The precipitation behaviors of γ″ and δ phases during high-temperature isothermal compressive deformation of Inconel 718 alloy are investigated under the strain rate of 2.2·10−4 s−1. It is found that the precipitation behaviors are tailored by deformation temperatures, and lead to the disparately abnormal deformation characteristics. Under the deformation temperature of 800 °C, the microstructure is composed of incoherent needle-shaped γ″ precipitates at grain boundaries and ultrafine spherical γ″ particles within grains, resulting in the exceptional decrease of flow stress with absence of DRX. When deformed at 900 °C, it becomes needle-shaped δ precipitates at grain boundaries and intragranular disc-shaped γ″ precipitates, and the DRX softening degree is lowered consequently.

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Precipitation behavior during high-temperature isothermal compressive deformation of Inconel 718 alloy

The microscopic defects that distributed randomly in metals are not only hard to detect, but also may inevitably cause catastrophic failure. Thus, autonomic probing and healing for damage inside metals continue to be a challenging. Here we show a novel approach for self-healing using electropulsing as a stimulus to trigger repairing of damaged metals. This is achieved via a process that through expelling absolutely currents, the microcrack causes them to be redistributed to form a concentrated and a diluted region around it, thereby inducing an extremely high temperature gradient and a large compressive stress, which drive material flow to close microcracks. Simultaneously, a large enough heat for bonding atoms was produced. That is, the microcrack as an empty cavity can be regarded as a special micro-device to shape a localized microscopic energy field, which in turn activates a healing process. The microstructure and mechanical property verified the extrinsic self-healing of a titanium alloy. The process is performed on a short timescale, is enable to detect automatically and act directly on the internal defects in metals, and to heal damage without any healing agent, long time heating as well as applied high pressure, offering unique advantages over conventional healing approaches.

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Self-healing of damage inside metals triggered by electropulsing stimuli.

Microstructure evolution and mechanical properties of micro-/nano-bimodal size B 4 C particles reinforced aluminum matrix composites prepared by SPS followed by HER

Effects of microporosity and precipitates on the cracking behavior in polycrystalline superalloy Inconel 718

Influence of solutioning on microstructure and hardness of hot isostatically pressed Astroloy

Healing Process of Casting Pores in a Ni-based Superalloy by Hot Isostatic Pressing

Impact of gas pressure on particle feature in Fe-based amorphous alloy powders via gas atomization: Simulation and experiment

The effects of solution concentration and temperature on the electrochemical behavior of the Fe-based amorphous (AMCs) coatings in NaCl solution were studied by using conventional electrochemical measurement and XPS analysis. Results indicated that as solution concentration and temperature increased, the current density for the Fe-based AMCs increased and the pitting potential decreased. This reduced corrosion resistance was derived from the decreased passivation index and polarization resistance, which contributed to the decrease of the induction time (tm) for the initiation of corrosion pit. The passive films formed on Fe-based AMCs exhibit two types’ semiconductors higher and lower the flat band potential. The decrease of protectiveness of the passive film was mainly correlated with the reduction of Cr2O3 content, the increase of carrier density and the decrease of the work function (WF).

Yutong Shi

Papers

Healing Process of Casting Pores in a Ni-based Superalloy by Hot Isostatic Pressing

Impact of gas pressure on particle feature in Fe-based amorphous alloy powders via gas atomization: Simulation and experiment

Sensitivity of Corrosion Behavior for Fe-Based Amorphous Coating to Temperature and Chloride Concentration

Suppression of grain boundary migration at cryogenic temperature in an extremely fine nanograined Ni-Mo alloy