Microstructure evolution, deformation behavior and processing performance of TNM TiAl alloy

The hot compression test, with a true strain of 0.9, was carried out at a temperature of 1100-1250 degrees C and a strain rate of 0.001-1 s(-1) by a Gleeble3800 thermal simulation testing machine for the as-cast TNM alloy. The stress-strain curves were recorded to measure the deformation resistance and deformation uniformity of the whole specimens, and the microstructure was analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) from the perspectives of the extent of recrystallization and the orientation and size of the grains. At lower strain rates, the strain is more uniform within the specimen. At higher temperatures, a complete recrystallization microstructure showing an equiaxed nearly lamellar (NL) structure with a weak texture can be obtained at a low strain rate, and a microstructure showing an elongated fine-grained NL structure without texture can be obtained at a high strain rate. The deformation mechanisms were analyzed, and the processing parameters were optimized by constructing empirical hot processing maps. The parameters 1200-1250 degrees C and 0.1-0.01 s(-1) are recommended for deformation to obtain a uniform fine grain structure economically without cracking of the specimen.

Automated summary

The hot compression test was conducted on the as-cast TNM alloy, with a true strain of 0.9, at temperatures ranging from 1100-1250 degrees C and strain rates of 0.001-1 s(-1) using a Gleeble3800 thermal simulation testing machine. The stress-strain curves were used to evaluate deformation resistance and uniformity, while microstructure analysis was performed using scanning electron microscopy and transmission electron microscopy. The study found that lower strain rates resulted in more uniform deformation within the specimen, and that different microstructures were achieved at different strain rates and temperatures. The deformation mechanisms were analyzed and empirical hot processing maps were used to optimize the processing parameters, with the recommended parameters being 1200-1250 degrees C and 0.1-0.01 s(-1) for achieving a uniform fine grain structure without specimen cracking.