SU1675062A1 - Method of producing transition metal aluminides - Google Patents

Abstract

The invention relates to powder metallurgy, in particular, to a method for producing transition metal aluminides. The aim of the invention is to improve the physicomechanical properties. A mixture of aluminum and transition metal powders is loaded into the attritor. The mixture is treated with balls at 20-80 ° C for 1.5-2 hours, then the temperature is raised to 400-600 ° C and the treatment is carried out for 0.5-1 hours after which the treatment temperature is reduced to 20-80 ° C for 24 hours. Powder of amorphous structure is obtained, which determines the higher physicomechanical properties of the material from the powders, an increase in tensile strength by 1.16-1.45 times, an relative elongation of 1 tabl.

Description

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The invention relates to powder metallurgy, in particular, to a method for producing aluminides of transition metals of mechanical alloying.

The purpose of the invention is to improve the physical and mechanical properties

The method is carried out as follows.

Balls and a mixture of powders of aluminum and one of transition metals are loaded into the attritor.

The mixture is treated in a shock-washing mode for 1.5-2 seconds at 20-80 ° C.

At this stage of processing, the formation of a composite powder AI + transitional Me occurs.

Then the capacity of the attritor is heated to 400-600 ° C and the composite powder is treated with an impact-abrasive effect in this temperature range, which leads to the formation of aluminide of a given stoichiometric composition in the crystalline and microcrystalline state.

At the third stage of processing, the capacity of the attritor is cooled to 20-80 ° C and aluminide powder is treated for 2-4 h. As a result of this processing, the aluminide goes into an amorphous state

As a result of processing by the proposed method, aluminides of transition metals of a given stoichiometric composition and amorphous and microcrystalline structure are formed.

At the first stage: at a temperature of less than 20 ° C, the treatment is impractical because the particles of the initial powders are not plastic at such temperatures, and therefore the formation of composite granules with a high area of mutual contact is impossible; heating above 8b ° C is impractical, since inclusions of incomplete stoichiometric composition may be formed in the volume of the formed composite particles; a processing time of less than 1.5 hours does not allow a composite powder to be homogeneous in composition; the processing time of more than 2 hours is impractical because the powder is completely homogeneous in composition.

In the second stage: when the processing temperature is less than 400 ° C, the complete transformation of the composite powder into an aluminide of a given composition does not occur; at a processing temperature of more than 600 ° C, the granules of the powder are sintered due to their melting, which makes it impossible to produce aluminide in the form of a powder; when the processing time is less than 0.5 h, the complete transformation of the composite powder into an aluminide of a given composition does not occur; the processing time of more than 1 hour is impractical because the formation of aluminum with a given composition is completed by this time.

At the third stage: at a temperature of less than 20 ° C, the treatment is impractical because the rate of amorphization of the adyuminide powder drops sharply at such temperatures; when heated to more than 80 ° C, the amorphous and microcrystalline state of the aluminide structure degrades into a crystalline state, followed by grain growth; the processing time of more than 4 hours is impractical because the process of transition to the amorphous and microcrystalline state of the aluminide structure by this time has been fully completed; with a treatment time of less than 2 hours, the structure obtained in the second aluminide stage does not disperse and thus the material does not reach the amorphous state in the entire volume.

The proposed method is carried out as follows.

The mark aluminum powder and nickel or titanium or niobium powder are loaded into an AT-4 type thermal attritor along with the remaining 5 mm diameter balls at a mass ratio of balls and mass of loaded powders of 19: 1.

In order to obtain nickel aluminide NIAIa, the mass ratio of the NI: AI powders is 42:58.

In order to obtain titanium aluminide T1A | 3, the ratio Ti: AI is 37:63.

. In order to obtain alumide niobium MbAl, the ratio Nb: AI is 53:47.

Downloadable powders are treated with shock-abrasive effect in vacuum at 20-80 ° C for 1.5-2 hours.

Then the attritor chamber is heated to 500-600 ° C and the mixture of powders is treated in this temperature range of 0.5-1 h. Then the attritor chamber is cooled to temperatures of 20-80 ° C and the mixture of powders is processed within 2-4 h.

The table shows the properties of aluminides after hydrodynamic pressing at 1162 ° C, pressure of 105 MP, and heat treatment of 1100 ° C according to the proposed and known methods.

The data show that the obtained powders are aluminides of nickel, titanium and niobium of a given stoichiometric composition, namely NIAIa, T1A1c. NbAla.

Characterized by increased tensile strength of 1.16-1.45 times, relative elongation in comparison with the known method.

Claims (1)

DETAILED DESCRIPTION A method for the production of transition metal aluminides by mechanical alloying, including loading powders into a ball mill, mechanical alloying during heating, characterized in that, in order to improve the physicomechanical properties, mechanical alloying is carried out in three stages: first, at a temperature 20-80 ° C for 1.5-2 hours, then at 500-600 ° C for 0.5-1 hours and 20-80 ° C for 2-4 hours.