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Isothermal compression tests were carried out on a Gleeble-3500D thermal simulation machine. The hot compression deformation behavior of a new hot-extruded Ni-Co-Cr-based powder metallurgy(P/M) superalloy at the temperatures from 1020℃ to 1110℃ with the strain rates from 10-3 s-1 to 1 s-1was systematically investigated. The flow stress curves were corrected by friction. Using the friction-corrected data, the constitutive equation for hot compression of the alloy and the flow stress model considering the strain compensation were established, respectively. At the same time, the hot processing map was built, and the hot deformation parameters of the alloy were optimized by combining with the analysis of the microstructure. The results show that apparently dynamic recrystallization occurs in the process of hot compression of the alloy, and the flow stress decreases with the decrease of strain rate or the increase of deformation temperature. The predicted values obtained from the developed flow stress model considering the strain compensation agree well with the experimentally friction-corrected data. According to the hot processing map and microstructural analysis, the reasonable hot working parameters of the alloy were suggested to be at the deformation temperatures of about 1076-1103℃ and the strain rates of about 10-3-10-2.77s-1.

Microstructure and mechanical properties of hot deformed (as-forged,as-rolled) Ti-45Al-7Nb-0.3W(atom fraction/%) alloy were investigated by optical microscope (OM), scanning electron microscope(SEM), transmission electron microscope(TEM) and tensile testing. Results show that the microstructure of as-cast Ti-45Al-7Nb-0.3W alloy is near lamellar, which is mainly composed of α2/γ lamellar colonies with a mean size of about 100μm,and minor γ as well as β phases located along the lamellar colonies boundaries. After hot canned forging, the lamellar colonies are broken and kinked. Compared with the as-cast alloy, the tensile strength of current as-forged alloy at room temperature increases by 77MPa, and the tensile strength at 800℃ increases by 36MPa. After the subsequent hot-pack rolling, the microstructure of the as-forged alloy is transformed into fine duplex microstructure with an average grain size of 25μm, mechanical properties of current as-rolled alloy are further improved, the room temperature tensile strength increases to 603MPa with the elongations of 1.0%, the tensile strength at 800℃ increases to 716MPa with the elongation of 3.6%.

Chronic actinic dermatitis (CAD) is a common debilitating photodermatosis. Patients often have to completely avoid outdoor activities, which severely impacts their quality of life. Phototherapy is effective for CAD and seems to increase patients' tolerance towards sunlight and consequently decrease the extent of disease. Unfortunately, the slower onset and time‐consuming nature of phototherapy limits the clinical application. Considering the effectiveness and time‐saving nature of ultraviolet (UV)‐A rush hardening in solar urticaria, we performed a pilot study to determine whether UV‐A rush hardening is effective in CAD. Six patients with CAD were exposed to multiple sessions of UV‐A for 4–5 days at 1‐h intervals/day. Subsequently, maintenance UV‐A exposure was performed at 1–2‐week intervals. Phototesting at baseline showed that three patients were sensitive to both UV‐A and ‐B, and the other three patients only showed UV‐A sensitivity. All of the patients responded well to UV‐A rush hardening and four (67%) maintained a good remission status after 1 year. The results of this pilot study suggest that UV‐A rush hardening phototherapy is effective and well tolerated in the treatment of CAD, while future larger prospective studies using objective scores of disease activity and quality of life are needed. [ABSTRACT FROM AUTHOR]