Исследовано микроструктурное строение интерметаллидных покрытий на стали 30 после испытания на жаростойкость термоциклическим способом. Для покрытий использованы интерметаллиды NiAl, Ni 3 Al и Ni. Показано, что основной причиной снижения жаростойкости интерметал-лидных покрытий является окисление по несплошностям в покрытиях. Ключевые слова: интерметаллидные покрытия, термоциклирование, алюминиды никеля, электроискровое легирование, жаростойкость, формирование оксидов.

In the paper there are shown results on roughness parameter decrease on the electrospark coatings of 20H13 and 30 steel surfaces by means of smoothing with the use of the plant for non-abrasive ultrasonic finishing (NUF). For the coating formation there were used Ni, Cu and an intermetallic alloy based on Ni3Al phase. At the NUF increase of coatings formed with the use of Cu there is a roughness growth caused with material “pickup” upon an indenter. It is determined that for smoothing the surfaces with electrospark coating with the assurance of roughness considerable decrease a six-fold NUF processing is required. A microstructure of the coating obtained with the use of anode material based on the Ni3Al alloy consists of columnar crystal grains the cross-section dimensions of which change from some mkm to several tens of nm. Crystal grains are directed mainly normally regarding a cathode surface. By means of micro-X-ray spectrum analysis there is defined an elementary composition of columnar crystal grains corresponding to the alloy of the Nix-Aly-Fez system which is alloyed with Cr and contains admixtures of Si and Mn. By means of the microstructure investigation of the coating smoothed surface in a number of areas there are revealed crystal grains with the signs of plastic deformation.

ИНТЕРМЕТАЛЛИДНЫЕ ПОКРЫТИЯ ПОСЛЕ ИСПЫТАНИЯ НА ЖАРОСТОЙКОСТЬИсследована структура интерметаллидных покрытий, сформированных методом электроис-крового легирования (ЭИЛ) на стали 30, после ис-пытания на жаростойкость при температуре 900 °С. В качестве материалов для покрытий использованы сплавы, полученные методом алюминотермии из оксидов. Методом микрорентгеноспектрального анализа на поперечных шлифах образцов стали с покрытиями изучен элементный состав различных структурных составляющих.Ключевые слова: алюминиды никеля, элек-троискровое легирование, композиционные покры-тия, жаростойкость.S.N. Khimukhin, V.V. Gostishchev, A.V. Medneva, Hosen Ri, E. H. Ri. INTERMETALLIC COATINGS AFTER HEAT RESISTANCE TESTThe structure of intermetallide coatings formed by a method of electro-spark alloying (ESA) is investigated on steel 30 after a test for heat-resistance at a temperature of 900ºC. As materials for coatings there were used alloys obtained from oxides by an alumothermy method. NiAl based alloys by Cr, Mo, W, separately and in complex. By a method of an electron microprobe analysis on cross microsections of samples of steel with coatings there was studied an element composition of different structural constituents. Maximum values of the mass transfer at the formation of coatings by material having NiAlCr are explained by presence in the structure of a softening phase containing an increased concentration of Cr (mass % 80-93). It is defined that the highest values of heat-resistance are ensured by a coating formed with the use of a complex doped alloy NiAl-Cr-Mo-W. A distinguishing feature of this coating is its fine structure and presense on borders of phases of structural constituents of alloying elements hindering diffusion.