 |
Visits: 86005704
AMS now reading: 1
|
|
|
|
|
 |
|
|
| Malcharcziková J., Kursa M., Beljajev I. V. |
| IMPACT OF CONDITIONS OF DIRECTIONAL CRYSTALLISATION BY BRIDGMAN METHOD ON PHYSICAL AND METALLURGICAL CHARACTERISTICS OF Ni3Al |
Abstract
Samples of Ni-Al alloys of various chemical composition were used for measurement. The samples were prepared by casting in vacuum induction furnace. Cast rollers with diameter 10 mm and length 95 mm were afterwards directionally crystallised by Bridgman method with vertical arrangement on special equipment in Vladimir (Russia). The cast pieces were inserted into electro-corundum tubes with specified apex angle. Various rates of directional crystallisation were used for verification of the most suitable conditions for obtaining of homogenous and mono-crystalline structure. Suitable samples were adjusted by turning to tensile rods, which were then used for tensile tests with measurement of acoustic emissions. For these tests there were used short tensile rods of round section with length 55 mm and with diameter of central part of the rod 5 mm. During all measurements there was monitored intensive acoustic emission with characteristic dependence on time and with correlation to individual stages of deformation. In all measurements it is possible to discern several areas on tensile diagram and characteristics of acoustic emission correspond with it. The formed fracture surfaces were investigated in detail. Grain orientation and micro-analysis of chemical composition were determined on cross section. Energy dispersive micro-analysis was used for precise determination of chemical composition, both with back-scattered electrons and with secondary electrons. X-ray diffraction with reflection method was used for determination of orientation of obtained grains. Metallographic evaluation was made on cross-sections and longitudinal sections. Some of the formed structures are highly homogenous, which was confirmed also by X-ray analysis.
|
| Keywords: Ni-Al based intermetallic compounds|tensile tests|acoustic emission|grain orientation| |
| No 4 (2006), p. 427-435 |
|
|
|
|
|
|
|
Editors and press
AMS online
