Patent ID: 12203153

DESCRIPTION OF EMBODIMENTS

Embodiments of the invention are now described by means of figures. However, the invention is not limited to these embodiments alone. The figures are for illustrative purposes and should not be construed as limiting the invention.

FIG.1schematically shows a part100according to the invention.

The part comprises a substrate10, made of nickel-based superalloy, and a sublayer, comprising a first layer11and a second layer12.

As described above, the first layer11comprises an average atomic content of aluminum greater than that of the substrate10.

The scope of the invention is not departed from, when the first layer11comprises a plurality of areas, each comprising an average atomic content of aluminum greater than that of the underlying area.

For example, it is possible for the first layer11to be composed of a plurality of areas each having a thickness comprised between 1 μm and 5 μm, the average atomic content of aluminum in each of the areas being greater than the average atomic content of aluminum of the underlying area.

For example, the average atomic content of aluminum in each area of the first layer can be up to 4% greater, or else between 2 and 4% greater than the average atomic content of aluminum of the underlying area.

Also, the part100comprises a second layer12whose average aluminum content is greater than the average aluminum content of the first layer11.

The scope of the invention is not departed from when the second layer12comprises a plurality of areas, each comprising an aluminum concentration greater than that of the underlying area.

For example, it is possible for the second layer12to be composed of a plurality of areas having a thickness comprised between 1 μm and 5 μm, the average aluminum content in each of the areas being greater than the average aluminum content of the underlying area.

For example, the average atomic content of aluminum in each area of the second layer can be up to 4% greater, or else between 2% and 4% greater than the average atomic content of aluminum of the underlying area.

It is also possible for the first11and the second layer12to each comprise several areas as described above.

In one embodiment not shown, the first area of the first layer comprises an average atomic content of aluminum 2 to 4% greater than the average atomic content of aluminum in the substrate, the second area of the first layer comprises an average atomic content of aluminum of 2 to 4% greater than the average atomic content of the first area, and so on until the second layer, the first area of which comprises an average atomic content of aluminum of 2% to 4% greater than the last area of the first layer, and so on until the last area of the second layer. As above, the areas have a thickness comprised between 1 μm and 5 μm.

The progressive variation of the aluminum content allows, in all the embodiments considered above, to obtain a sublayer whose upper portion has an average atomic content of aluminum greater than that of the substrate, while minimizing the interdiffusion effects or the creation of secondary reaction areas thanks to a progressive variation of the average atomic content of aluminum.

As described above, it is understood that the last area of the second layer comprises the γ-Ni, γ′-Ni3Al and β-NiAl phases.

In one embodiment, the first layer11comprises between 1 and 4 areas, and the second layer12comprises between 1 and 4 areas.

In one embodiment, the first layer11comprises between 1 or 2 areas, and the second layer12comprises between 1 or 2 areas.

In one embodiment, the first layer11comprises a single area, and the second layer12comprises a single area.

It has also been observed that a sublayer as described above allows, if desired, to deposit a thermal barrier layer on the face opposite the substrate of the second layer, in particular guaranteeing good adhesion of the latter.

The gradual increase in the average atomic content of aluminum in a sublayer as proposed allows to ensure that each of the layers forming the sublayer is sufficiently close in composition to have a high adhesion with the directly underlying layer. The gradual increase allows to go from the first layer to the second layer without having to change the deposition method. Indeed, the β-NiAl phase appears naturally at high aluminum contents and thus one simply goes from the first to the second layer.

In addition, the presence of numerous areas in the first and second area increases the number of grain boundaries, which further slows down the interdiffusion of nickel or aluminum between the layers.

In one embodiment, chromium is also present in the first and second layers. The amount of chromium can be adjusted depending on the exact properties desired for the sublayer.

In one embodiment, the chromium content in each of the first and second layers varies opposite to the aluminum content.

In one embodiment, the increase in the average atomic content of aluminum in the metal sublayer or, where applicable, in each of the areas of each of the layers of the sublayer is fully compensated by a decrease in the average atomic content of chromium in said sublayer.

In one embodiment, the average atomic content of chromium in a layer, or where appropriate an area of a layer, can be comprised between 7% and 17%.

Of course, the chromium content is chosen such that it does not affect the desired γ/γ′ or γ/γ/β structures for the first and second layers.

FIG.2is a micrograph obtained by scanning electron microscopy of a part according to one embodiment of the invention.

The substrate20is covered with a first layer21and a second layer22.

On the micrograph shown inFIG.2, the γ and γ′ phases211appear lighter than the β phases221.

In one embodiment, the deposition can be carried out by physical vapor deposition. Mention may in particular be made of deposition methods by cathode sputtering, by pulsed laser ablation, by Joule evaporation or else by electron impact.

Preferably, the deposition method is selected from magnetron cathode sputtering or evaporation.

FIG.3schematically shows a device allowing to carry out a deposition by magnetron cathode sputtering.

In a chamber301, a gas is introduced through the inlet306and a plasma is generated between the target305disposed near a magnet304and the substrate311.

For example, the following parameters, taken in their usual definition for a magnetron cathode sputtering method, allows to obtain a sublayer conforming to a part of the invention. The ion bombardment can be carried out with a potential comprised between −200 V to 400 V for 10 to 30 minutes. The deposition is performed at a power density comprised between 3 to 10 W/cm2, heating during deposition is comprised between 200 to 700° C., the bias is comprised between −150 V to −300 V, and the pressure is comprised between 0.1 and 2.0 Pa.

In one embodiment, several targets corresponding to the materials to be deposited are introduced into the physical vapor deposition chamber. It is thus possible to create the sublayer layer by layer, or if necessary area after area, in a single enclosure, by adjusting the deposition conditions to ensure that the composition of each layer, or if necessary each area of the first layer then the second layer, has the desired composition.

EXAMPLE

Several compositions comprising elements in different contents were simulated with the JPMATPro-V10 software. For each of these compositions, the content of each of the γ-Ni, γ′-Ni3Al and β-NiAl phases was determined by the software.

In table 1, the contents of the elements are given in atomic percentages and the contents of the phases are expressed in mass percentages.

It is observed that the content of each of the γ-Ni, γ′-Ni3Al and β-NiAl phases of compositions 1 to 3 satisfy the desired conditions for the second layer of claim1, while compositions 4 and 5 do not satisfy said conditions.

TABLE 1NiAlCrCoHfPtSiTaWβγγ′1Base221010.630.80.30.32020602Base24910.620.80.30.33817453Base2392.211010.30.53010504Base280003000100905Base28100.330.20022078

The table above shows that it is not the individual content of each element, but an effect of the content of each of the elements which is decisive in the presence or absence of the γ-Ni, γ′-Ni3Al and β-NiAl phases, and the relative proportion of each of them.