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Mechanical alloying (MA) method was applied to nitride Fe–18Cr–11Mn stainless steel powders through aerating nitrogen circularly. Both the MA process and increasing nitrogen pressure circularly caused the expansion of nitrogen solubility in Fe. The microstructure of powders was affected by the milling time. The phase transformation of α-Fe to γ-Fe occurred during the MA process. The grain size of powder decreased, while the internal lattice strain increased by increasing the milling time and cycles of aerating nitrogen. The as-milled powder could obtain a fully austenitic structure after sintering and subsequent water quenching. The sintered samples had better density and higher microhardness when the powders milled for more time. The formation mechanism of nitriding of stainless steel powders using MA method in nitrogen was presented.

To analyze structural dynamic response of rotary ultrasonic motor under high impact load, a theoretical model is established in this paper. A rotary ultrasonic motor includes two main components: stator and rotor. According to structure form and movement principle, they can be simplified as annular plates. When the system is imparted an impact load, dynamic displacement response of stator and rotor can be obtained. The damage to stator and rotor is analyzed in theory. It gave agreement with simulation and experimental result. Finally, influence of various structure parameters on the deformation of stator and rotor is analyzed and some suggestions on improving performance of rotary type ultrasonic motor are proposed.

Cellular metallic glasses (MGs) can be good candidates for structural and functional applications due to their light weight, enhanced ductility and excellent energy absorption performance.

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