Microstructure modification and precipitation strengthening for Mg−6Zn−1Mn−4Sn−0.5Ca through extrusion and aging treatment

The microstructure revolution and mechanical properties of as-extruded and peak-aged Mg−6Zn−1Mn−4Sn−0.5Ca(ZMT614−0.5Ca)alloy were studied by OM,SEM,TEM,hardness testing and tensile testing.The results showed that the as-cast ZMT614−0.5Ca alloy mainly consisted of α-Mg,Mg−Zn and CaMgSn phase.The hot extrusion process effectively refined the microstructure and led to a completely dynamic recrystallized microstructure.The average grain size of as-extruded alloy was^4.85μm.After solution treatment,remained CaMgSn with high melting point played a significant role in pinning effect and impeding the migration of grain boundary.After aging treatment,peak-aged ZMT614−0.5Ca alloy exhibited a good combination of strength and ductility,with yield strength,ultimate tensile strength and elongation being 338 MPa,383 MPa and 7.5%,respectively.The yield strength of the alloy increased significantly by around 36%compared with that in as-extruded condition,which should be attributed to the precipitation strengthening of β'phase.

Microstructural evolution and mechanical properties of an Fe–18Ni–16Cr–4Al base alloy during aging at 950°C

The development of Gen-IV nuclear systems and ultra-supercritical power plants proposes greater demands on structural materials used for key components. An Fe-18Ni-16Cr-4Al（316-base） alumina-forming austenitic steel was developed in our laboratory. Its micro- structural evolution and mechanical properties during aging at 950℃were investigated subsequently. Microstructural changes were charac- terized by scanning electron microscopy, electron backscatter diffraction, and transmission electron microscopy. Needle-shaped NiAI parti- cles begin to precipitate in austenite after ageing for 10 h, whereas round NiA1 particles in ferrite are coarsened during aging. Precipitates of NiAI with different shapes in different matrices result from differences in lattice misfits. The tensile plasticity increases by 32.4% after aging because of the improvement in the percentage of coincidence site lattice grain boundaries, whereas the tensile strength remains relatively high at approximately 790 MPa.

A new classification for hepatocellular carcinoma with hepatic vein tumor thrombus

Background:Hepatic vein tumor thrombus(HVTT)is a significant poor risk factor for survival outcomes in hepatocellular carcinoma(HCC)patients.Currently,the widely used international staging systems for HCC are not refined enough to evaluate prognosis for these patients.A new classification for macroscopic HVTT was established,aiming to better predict prognosis.Methods:This study included 437 consecutive HCC patients with HVTT who underwent different treatments.Overall survival(OS)and time-dependent receiver operating characteristic(ROC)curve area analysis were used to determine the prognostic capacities of the new classification when compared with the different currently used staging systems.Results:The new HVTT classification was defined as:type I,tumor thrombosis involving hepatic vein(HV),including microvascular invasion;type II,tumor thrombosis involving the retrohepatic segment of inferior vena cava;and type III,tumor thrombosis involving the supradiaphragmatic segment of inferior vena cava.The numbers(percentages)of patients with types I,II,and III HVTT in the new classification were 146(33.4%),143(32.7%),and 148(33.9%),respectively.The 1-,2-,and 3-year OS rates for types I to III HVTT were 79.5%,58.6%,and 29.1%;54.8%,23.3%,and 13.8%;and 24.0%,10.0%,and 2.1%,respectively.The time-dependent-ROC curve area analysis demonstrated that the predicting capacity of the new HVTT classification was significantly better than any other staging systems.Conclusions:A new HVTT classification was established to predict prognosis of HCC patients with HVTT who underwent different treatments.This classification was superior to,and it may serve as a supplement to,the commonly used staging systems.

Liver resection versus intensity-modulated radiation therapy for treatment of hepatocellular carcinoma with hepatic vein tumor thrombus:a propensity score matching analysis

Background:The presence of hepatic vein tumor thrombus(HVTT)is a major determinant of survival outcomes in hepatocellular carcinoma(HCC)patients.This study compared survival outcomes between liver resection(LR)and intensity-modulated radiation therapy(IMRT)in HCC patients with HVTT.Methods:Data from patients who underwent LR or IMRT for HCC with HVTT at the Eastern Hepatobiliary Surgery Hospital were retrospectively analyzed.Their survival outcomes were compared before and after propensity score matching(PSM).Results:Three hundred and seven HCC patients with HVTT who underwent either LR(n=140)or IMRT(n=167)were enrolled.PSM matched 82 pairs of patients.The overall survival(OS)and recurrence-free survival(RFS)rates were significantly higher for patients in the LR group than those in the IMRT group.On subgroup analysis,significantly better survival outcomes were obtained after LR than IMRT in patients with peripheral type of HVTT(pHVTT)and major type of HVTT(mHVTT).However,similar survival outcomes were obtained after LR and IMRT when the HVTT had developed into inferior vena cava tumor thrombus(IVCTT).Conclusions:LR resulted in significantly better survival outcomes in HCC patients with HVTT when compared to IMRT.Once the HVTT had developed IVCTT,LR and IMRT resulted in similarly bad survival outcomes.