Zeng Liying

Processing Map of One Kind of Metastable β Titanium Alloy

In order to exploit the potential hot deformation ability of metastable β titanium alloy Ti-B19 the isothermal compression behavior was investigated by a Gleeble-1500 thermal simulator in the temperature range of 750–1000 °C at an interval of 50 °C and strain rate from 0.001 to 10 s−1. The results indicate that the flow stress of the alloy increases with increasing of the strain rate at a given temperature, and decreases with the increment of temperature at a given strain rate. The processing map for the alloy obtained at strain of 0.6 can be divided into three domains. The first is the one in the temperature range of 700∼800 °C and the strain rate range of 0.001–0.1 s−1, with a peak efficiency of 42% at about 750 °C and 0.01 s−1. The flow curves in this domain present a single peak or oscillation in the flow curves before continuous softening appears. The second is the one in the temperature range of 800–1000 °C and the strain rate range of 0.001–0.1 s−1, with efficiency from 29% to 36%. The flow curves in this domain present a single peak or oscillation in the flow curves before reaching steady state. Recrystallized structures can be found, which is a typical dynamic recrystallization zone. The third one is a flow instable domain at the temperature lower than 800 °C and the strain rate above 0.1 s−1, or at the temperature higher than 800 °C and strain rate above 10 s−1. The adiabatic shear bands (ASBs) and flow inhomogeneous zone of β phases can be observed.

Microstructure of ordered Pd–8at.%Y alloys

Abstract The microstructure of palladium–yttrium alloys has been investigated in this paper, the two alloys were the Pd–7.52at.%Y alloy and Pd–8.22at.%Y alloy, respectively. The Pd–Y alloy ingots were prepared by melting the yttrium powder and palladium powder in a vacuum induction furnace. The resultant alloys were homogenized at 950°C for 6 h. Then cold rolled to produce foil. Some of them were quenched into water from 900, 920 and 940°C, respectively. Finally given a vacuum anneal at 750°C for 40 min and furnace cooled to produce the material in long-range-ordered (LRO) condition. There was an inflection on the curve of electrical resistance vs. temperature, which indicates that the anomaly electrical resistance variation is due to an order–disorder transition. The results of XRD show that Pd 3 Y typed LRO super-lattice existed in as-annealed samples. After annealing, the average grain size of Pd–8at.%Y alloys become smaller, the grains distribute unequally, and the grain scale for as-quenched and as-annealed samples was 750/mm 2 and 760/mm 2 , respectively. Microstructure was studied by optical and transmission electron microscopy. Anti-phase domain boundary (APB) was found in the as-annealed alloys. The cell-like structures in the TEM photo were not complete.