B. Peterson, P. Collins, V. Levit, H. Fraser, The Ohio State University, Columbus, OH
The composition of the alloy Timetal 21S has been selected as a baseline for the development of a new high temperature beta titanium alloy. A combinatorial approach employing directed laser deposition of elemental powders has been used to produce a number of test coupons that represent a controlled variation of alloy composition. Subsequently, the creep properties are assessed using an Instron ETMT instrument operating in a constant load mode, and represented by their minimum creep rates (i.e., the tests are terminated as soon as minimum creep is achieved). The microstructures of the test coupons are characterized using rigorous stereological techniques. These data populate the databases used to train and test fuzzy logic based models for predicting the creep properties. In addition to the base elements (Ti, Mo, Nb, Al, and Si), neutral elements (Zr and Sn), beta-stabilizers (W), and dispersoid formers (B, C, Ge) are being tested as alloying additions. The most promising alloying additions have been identified. Based on the results of the coupled mechanical tests and computer models, a new group of alloys for application in high temperature thermal protection systems are being developed.
Summary: The composition of the alloy Timetal 21S has been selected as a baseline for the development of a new high temperature beta titanium alloy. A combinatorial approach employing directed laser deposition of elemental powders has been used to produce a number of test coupons that represent a controlled variation of alloy composition. Subsequently, the creep properties are assessed using an Instron ETMT instrument operating in a constant load mode, and represented by their minimum creep rates (i.e., the tests are terminated as soon as minimum creep is achieved). The microstructures of the test coupons are characterized using rigorous stereological techniques. These data populate the databases used to train and test fuzzy logic based models for predicting the creep properties. In addition to the base elements (Ti, Mo, Nb, Al, and Si), neutral elements (Zr and Sn), beta-stabilizers (W), and dispersoid formers (B, C, Ge) are being tested as alloying additions. The most promising alloying additions have been identified. Based on the results of the coupled mechanical tests and computer models, a new group of alloys for application in high temperature thermal protection systems are being developed.
