Boron 첨가에 의한 Ni-32at.%Al 합금의 내마모 및 내산화 특성 = Transformations;Effect of Boron Addition on the Wear and Oxidation Properties of the Ni-32at.%Al Alloy

다국어 초록 (Multilingual Abstract)

The effect of boron addition on the wear and oxidation resistance of nickel aluminides was investigated. Wear tests of various heat-treated specimens at room temperature and at 500℃ were performed under no lubricant condition in air by using a ball-on-disk type tribotester. Isothermal oxidation tests were made at 1100℃ in air flowing at the rate of 70cc/min. and at 1000℃ in air by using TGA. Experimental results from wear tests showed that boron-added nickel aluminide had remarkably improved wear resistance at both temperatures. Especially, the minimum weight loss and the minimum wear volume in solutionized and aged boron-added specimen were measured from the wear test at 500℃. On the contrary, the addition of boron to the nickel aluminides has affected the oxidation resistance of the aluminides adversely. Ni-32Al-0.5B aluminide showed poorer oxidation resistance than Ni-32Al aluminide during the isothermal oxidation test. Although both types of aluminides revealed a parabolic oxidation behavior and the formation of Al₂O₃ on the surface, the differences in the oxidation resistance between the aluminides with and without boron addition seemed to be attributed to the microstructural difference between the aluminides. An accelerated oxidation along the thin layer of Ni₃Al along the grain boundary observed in the microstructure of the Ni-32Al-0.58 aluminide could be attributed to the poor oxidation resistance compared with the Ni-32Al showing no grain boundary Ni₃Al phase.