Perovskite phase lead zirconate titanate thin film deposition on Pt/SiO 2 /Si substrate at low temperature
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Fig. 4—Effect of temperature on the area fraction of damaged silicon particles in A356 alloy.
nificantly with the decrease in the temperature. The strength of the alloy and hardening rate increase with the decrease in the temperature. This gives rise to a stress state with higher stress triaxiality, which leads to an increase in the damage rate of silicon particles. These observations are in agreement with those of Yeh and Liu,[7] who varied the strength of A357 alloy through heat treatment and measured fraction of broken silicon particles in the failed tensile test specimens having different strengths. They observed that at room temperature, the rate of fracture of silicon particles increases with the strength of the alloy. As the rate of silicon particle damage increases significantly with inverse temperature, contribution of this fracture micromechanism to crack initiation and propagation is expected to be higher at lower temperatures. It is observed that large and elongated silicon particles fracture more frequently.[7,8] Therefore, a significant improvement in cryogenic ductility and other fracture related properties of the Al-Si-Mg alloys may be possible through refinement of silicon particle size via modification. However, as the silicon particle damage rate decreases with the increase in the temperature, the size and shape of silicon particles may not be important microstructural parameters in controlling hightemperature ductility and fracture related attributes of AlSi-Mg alloys.
The authors thank Richard Osborne (General Motors), Srinath Viswanathan (Oak Ridge National Laboratory), and Jerry Cole (Ford Motor Co.) for numerous useful discussions and suggestions. They also thank A. Schneider (Chrysler Corporation), for casting the A356 alloy plate, and the West Moreland Mechanical Testing Laboratory for performing the tensile tests. Two of the authors (AMG and
METALLURGICAL AND MATERIALS TRANSACTIONS A
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Perovskite Phase Lead Zirconate Titanate Thin Film Deposition on Pt/SiO2/Si Substrate at Low Temperature CHUNG CHENG CHANG The thin
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