Retarding the precipitation of η phase in Fe-Ni based alloy through grain boundary engineering

It is important to inhibit the precipitation of η phases in precipitation strengthened Fe-Ni based alloys,as they will deteriorate not only the mechanical property but also the hydrogen resistance.The present investigation shows that grain boundary engineering(GBE) can retard the formation and growth of ηphase in J75 alloy.After GBE treatment with 5% cold rolling followed by annealing at 1000℃ for 1 h,the fraction of special boundaries(SBs) increases from 38.4% in conventional alloy to 77.2% and the fraction of special triple junctions increases from 10% to 74%.During 800℃ aging treatment,quite amount of cellular η phases adjacent to random grain boundary(RGB) will be found in conventional alloy,and only a few small η phases have been observed in GBE treatment alloy subjected to the same aging treatment for long time.The reason for GBE in inhibiting precipitation of η phase can be attributed to not only introducing high fraction of SBs but also breaking the connectivity of RGB networks.As nucleation and growth of η phases on SBs are difficult due to their lower Ti concentration and diffusion rate,and the disruption of RGB networks reduces supply of Ti atoms to the η phases significantly,which impedes their growth at RGB.

Immune microenvironment-reshaping Au@Bi_(2)Te_(3) nanoparticles for spectral computed tomography/photoacoustic imaging-guided synergetic photo/radio/immunotherapy

Radiotherapy(RT)mediated tumor immunogenicity offers an opportunity for simultaneous RT and immunotherapy via immunogenic cell death(ICD),which releases damaged-associated molecular patterns and generates“eat me”signals for the innate immune system to modulate the immunogenicity.However,tumor hypoxia significantly reduces the therapeutic efficacy of RT and hampers its mediation of ICD induction.Herein,Au@Bi_(2)Te_(3)-polyethylene glycol(PEG)was rationally constructed as theranostic nanozymes for mild photothermal therapy,tumor hypoxia modulation,and RT adjuvant cancer immunotherapy.The tumor-specific production of oxygen could not only augment the effects of RT by enhanced reactive oxygen species(ROS)generation,but also reduce hypoxia-related cytokines and downregulate programmed cell death-ligand 1(PD-L1)to unleash immune-enhancing T cells.Moreover,Au@Bi_(2)Te_(3)-PEG could act as an immune-blocking inhibitor by efficient ICD induction with the combination of mild-photothermal therapy+RT to inhibit the tumor immune escape and improve antitumor immune response.Increased amounts of CD^(4+) and CD^(8+) Tcells and elevated levels of cytokines could be observed that eventually led to effective post-medication inhibition of primary and abscopal tumors.Spectral computed tomography/photoacoustic imaging allowed noninvasive and real-time tracking of nanoparticle(NP)accumulation and oxygenation status at tumor sites.Collectively,Au@Bi_(2)Te_(3)-PEG NPs could serve as effective theranostic nanoregulators with remarkable synergistic mildphotothermal/RT/immunotherapy effects that helped reshape the immune microenvironment and had remarkable molecular imaging properties.