CN103572085A - Preparation method of TiAl-base alloy - Google Patents

Abstract

The invention discloses a preparation method of a TiAl-base alloy. The preparation method is characterized by comprising the following steps: (1) evenly mixing TiAl3 powder with the granularity of 300 meshes and Ti powder with the granularity of 500 meshes at a mass ratio of (1:2)-(1:5); (2) performing cold pressing on the mixture under a pressure of 800MPa so as to obtain billets and encapsulating the billets into a low-carbon steel sleeve when the vacuum degree is 5*10<-2>Pa; (3) heating the cold-pressed billets with the low-carbon steel sleeve to 1050-1250 DEG C at a heating speed of 50 DEG C/min, and putting the cold-pressed billets with the low-carbon steel sleeve into a mold to extrude and form after carrying out heat preservation for 30-60 minutes. The preparation method is simple in process and low in cost; the problem of high cost of a pre-alloying method is solved; meanwhile, the problem of volume expansion when the TiAl alloy is prepared from Ti and Al elements by a powder method is avoided; the TiAl-base alloy with high compactness and even and fine tissue can be obtained.

Description

A kind of preparation method of TiAl base alloy

Technical field

The invention belongs to high-temperature structural material preparing technical field, relate in particular to a kind of preparation method of TiAl base alloy.

Background technology

TiAl base alloy has the essential series of features of high-temperature structural material, has caused numerous scientific research personnel's attention, and various countries have also dropped into a large amount of human and material resources, financial resources are studied, and has obtained some achievements.TiAl base alloy has the outstanding advantages such as density is light, high temperature resistance, resistance to oxidation, shows very wide application prospect in aerospace field, becomes the preferred material of advanced military aircraft engine pneumatic plant and low-pressure turbine blade.

Precision-investment casting is current most widely used TiAl base Alloy Forming technology, can once cast part complex-shaped, thin-walled, and foundry goods has high dimensional precision and low surfaceness.CN101457331A adopts a consumable to add induction suspending investment cast and makes blank, and blank obtains TiAl alloy bar material after jacket-Intermittent pneumatic compression.But casting time exists the chemical activity of melt strong, gravity head is little, fill the problems such as type mobility is not high.

It is raw material that powder metallurgic method be take simple substance or powdered alloy, adopt conventional plastic processing method to carry out consolidation to powder, and then through sintering, can directly obtain the TiAl base alloy product of desired shape, realize the near-net forming of product simultaneously, thereby avoided follow-up plastic working or mechanical workout to TiAl base alloy, and the alloy obtaining compare with casting organize more even, tiny.Powder metallurgy is prepared TiAl base alloy prior can be divided into element powders method and pre-alloyed powder method by raw material powder.Ti, Al element powders legal system are during for TiAl base alloy, and the inclined to one side spread coefficient between Ti, Al element differs greatly, and generate Frenkel hole, in pressureless sintering process, generate TiAl ₃the middle phenomenon that causes mutually blank generation volumetric expansion.Pre-alloyed powder method compare with element powders method composition evenly, oxygen and foreign matter content is low, mechanical property is good, but raw material powder cost is high.It is raw material that CN101240382A be take Ti powder, Al powder and other microelement powder, and cold-press moulding has obtained high dense TiAl-base alloy after 1200 ~ 1400 ℃ of sintering.But Al is different from Ti spread coefficient, in sintering process, easily produce volumetric expansion, the homogeneity of ingredients of alloy and homogeneity of structure are difficult to guarantee.

Summary of the invention

The object of this invention is to provide a kind of density high, homogeneous microstructure is tiny, the preparation method of the TiAl base alloy of good mechanical properties.

Preparation method's step of TiAl base alloy of the present invention is as follows:

1. by 300 object TiAl ₃powder mixes according to mass ratio 1:2 ~ 1:5 with 500 object Ti powder;

2. under 800MPa pressure, be cold-pressed into after base, in vacuum tightness 5 * 10 ^-2under Pa, enclose low-carbon (LC) steel bushing;

3. with the heat-up rate of 50 ℃/min, the blank of colding pressing with low-carbon (LC) steel bushing is warming up to 1050 ~ 1250 ℃, is incubated after 30 ~ 60min, put into mould extrusion molding.

Compared with prior art, beneficial effect of the present invention is that the present invention adopts Ti and TiAl ₃for raw material, avoided Ti, Al element powders method to generate TiAl ₃, therefore can there is not Study of Volume Expansion in the reaction of middle phase.The invention solves the problem of prealloy method raw material powder cost costliness, with lower cost, prepare density and be greater than 98%, ultimate compression strength is at 1717 ~ 2102MPa, the TiAl base alloy of average grain size below 40 μ m.

Embodiment

Embodiment mono-

By 300 object TiAl ₃powder and 500 object Ti powder are 1:2 batching in mass ratio, on mixed powder machine, mixes the powder that obtains mixing for 72 hours; The powder mixing, under 800MPa pressure, is cold-pressed into after base, in vacuum tightness 5 * 10 ^-2under Pa, enclose low-carbon (LC) steel bushing; Heat-up rate with 50 ℃/min is warming up to 1050 ℃ by the blank of colding pressing with low-carbon (LC) steel bushing, after insulation 30min, puts into mould extrusion molding, makes density 98%, average grain size 20 μ m, the TiAl base alloy of ultimate compression strength 1800MPa.

Embodiment bis-

By 300 object TiAl ₃powder and 500 object Ti powder are 1:3 batching in mass ratio, on mixed powder machine, mixes the powder that obtains mixing for 72 hours; The powder mixing, under 800MPa pressure, is cold-pressed into after base, in vacuum tightness 5 * 10 ^-2under Pa, enclose low-carbon (LC) steel bushing; Heat-up rate with 50 ℃/min is warming up to 1050 ℃ by the blank of colding pressing with low-carbon (LC) steel bushing, after insulation 30min, puts into mould extrusion molding, makes density 98%, average grain size 20 μ m, the TiAl base alloy of ultimate compression strength 1850MPa.

Embodiment tri-

By 300 object TiAl ₃powder and 500 object Ti powder are 1:2 batching in mass ratio, on mixed powder machine, mixes the powder that obtains mixing for 72 hours; The powder mixing, under 800MPa pressure, is cold-pressed into after base, in vacuum tightness 5 * 10 ^-2under Pa, enclose low-carbon (LC) steel bushing; Heat-up rate with 50 ℃/min is warming up to 1150 ℃ by the blank of colding pressing with low-carbon (LC) steel bushing, after insulation 30min, puts into mould extrusion molding, makes density 99%, average grain size 25 μ m, the TiAl base alloy of ultimate compression strength 2102MPa.

Embodiment tetra-

By 300 object TiAl ₃powder and 500 object Ti powder are 1:2 batching in mass ratio, on mixed powder machine, mixes the powder that obtains mixing for 72 hours; The powder mixing, under 800MPa pressure, is cold-pressed into after base, in vacuum tightness 5 * 10 ^-2under Pa, enclose low-carbon (LC) steel bushing; Heat-up rate with 50 ℃/min is warming up to 1200 ℃ by the blank of colding pressing with low-carbon (LC) steel bushing, after insulation 30min, puts into mould extrusion molding, makes density 98.5%, average grain size 35 μ m, the TiAl base alloy of ultimate compression strength 2010MPa.

Embodiment five

By 300 object TiAl ₃powder and 500 object Ti powder are 1:5 batching in mass ratio, on mixed powder machine, mixes the powder that obtains mixing for 72 hours; The powder mixing, under 800MPa pressure, is cold-pressed into after base, in vacuum tightness 5 * 10 ^-2under Pa, enclose low-carbon (LC) steel bushing; Heat-up rate with 50 ℃/min is warming up to 1200 ℃ by the blank of colding pressing with low-carbon (LC) steel bushing, after insulation 60min, puts into mould

Extrusion molding, makes density 98%, average grain size 40 μ m, the TiAl base alloy of ultimate compression strength 1717MPa.

Claims (1)

1. a preparation method for TiAl base alloy, is characterized in that preparation method's step is as follows:

1. by 300 object TiAl ₃powder and 500 object Ti powder in mass ratio 1:2 ~ 1:5 mix;

2. under 800MPa pressure, be cold-pressed into after base, in vacuum tightness 5 * 10 ^-2under Pa, enclose low-carbon (LC) steel bushing;

3. with the heat-up rate of 50 ℃/min, the blank of colding pressing with low-carbon (LC) steel bushing is warming up to 1050 ~ 1250 ℃, is incubated after 30 ~ 60min, put into mould extrusion molding.