JPH03199330A - Production and agglomeration method of TiAl-based intermetallic compound alloy - Google Patents

Abstract

PURPOSE:To avoid troubles at the time of melting, such as bumping, adhesion of metal, and hanging and to obtain an alloy minimal in contamination with oxygen and free from the remaining of shrinkage cavity by previously subjecting Ti as raw material to degassing treatment at the time of refining the alloy by using a calcia crucible. CONSTITUTION:A raw material consisting of, by atom, 48-70% Ti and 30-52% Al is melted in a calcia crucible and a TiAl-base intermetallic compound is refined. At this time, after hydrogen gas in Ti is sufficiently released by previously applying heating to Ti as raw material at about 700-1000 deg.C in a degree of vacuum higher than 10<-1>mmHg for several hours in the calcia crucible, the above Ti is melted together with Al as raw material in vacuum or in an Ar atmosphere.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing and agglomerating IMAI-based intermetallic alloys. This alloy has a specific gravity of 3.8 (TiAl) to 4.
2 (Ti2Al), it is lightweight and can be heated from 500℃ to 900℃.
Because of its excellent specific strength in the high-temperature range, it is expected to be used in aircraft components that require light weight and heat resistance, high-speed rotating bodies for general industry, and other applications.

[Prior art] In order to melt a TiAl-based intermetallic compound alloy in a crucible, T
Since i is a metal with extremely strong affinity for oxygen,
Calcia (Cab) is used as the crucible material, and the crucible is generally melted in a vacuum or in an Ar gas atmosphere. When Tt and AI raw materials are charged into a calcia crucible and melted, the low melting point AI melts first, followed by the high melting point Ti.
However, since Ti raw materials generally contain a large amount of hydrogen gas (20 to 40 ppm) and the hydrogen solubility of AI is low (see Figure 2), hydrogen gas is generated violently when Ti is dissolved. Problems such as splashing of molten metal due to bumping, adhesion of metal to the crucible wall, and hanging on shelves are likely to occur. In addition, the violent agitation of the molten metal due to the generation of hydrogen gas causes erosion of the crucible wall, causing the inclusion of calcia-based inclusions in the molten metal and an increase in the amount of oxygen in the molten metal.

When making ingots of this alloy, since Ti is a metal with a high affinity for oxygen, refractories containing silica cannot be used in the feeder section, and normally a feeder frame made of refractory is not used. Then, the metal is poured into the metal mold. In this case, shrinkage pores due to volumetric contraction when the molten metal solidifies remain in the ingot body, and the yield of the ingot is significantly reduced.

[Problems to be Solved by the Invention] The present invention attempts to solve the above-mentioned problems in the crucible melting process and the ingot forming process using a mold for TiAl-based intermetallic compound alloys.

[Means for Solving the Problems] The configuration of the present invention for solving the above problems is as described in the claims. To summarize its characteristics, 1. Ti raw material is prepared in advance in a calcia crucible at 700~
By heating for several hours at a temperature of 1000°C and a degree of vacuum higher than 10' mg + IIg to sufficiently release the hydrogen gas in the titanium raw material, the titanium raw material is melted together with the AI raw material in a vacuum or Ar atmosphere in the crucible. , gas generation is eliminated when the Ti raw material is melted, and problems such as bumping, metal adhesion, shelving, and molten metal contamination are prevented.

2. Knead calcia powder with methanol or ethanol,
By using a sleeve-shaped feeder frame made by firing at 900 to 1000°C after shaping and solidification, the aim is to prevent the formation of shrinkage holes during the solidification process of the ingot without contaminating the molten metal. .

[Example] Hereinafter, the present invention will be specifically explained with reference to Examples.

Example 1 JI 82 pure, T i 51 atomic % and high purity A149
Atom % was used as a raw material and melted in a 99% calcia crucible using a 10 kg high-frequency vacuum induction melting furnace to melt a TiAl-based intermetallic compound alloy. The degree of vacuum during melting was 2 to 5 x 10' m, 511 g until aluminum burn-through, and thereafter melting was carried out in an Ar atmosphere of 10 to 15 m, 11 g.

Lot A is Ti raw material at 700℃X 5HrX 10'
Vacuum heat treatment was performed at ~10' imHg, and Lot B was heated at 900°C x 2 Hr x 10'~10-' ggm.
Hg heat treatment was performed.

Lot C was melted using untreated Ti raw material.

The measured values of the amount of residual hydrogen before and after the de[H] treatment are shown for the Ti raw material of each loft.

Each loft starts with a new crucible and the melt weight is 1
Each 10 to 14 lysis was performed using approximately 3.7 kg per session. FIG. 1 shows the relationship between the number of times of dissolution and the amount of oxygen for each of the above samples.

Table 1 Ti raw material before and after de-treatment [Old amount measurement example 2 Molten metal melted under the conditions of lot A above was poured into a cast iron mold using a calcia feeder frame (bottom diameter Box's, top diameter 70
-■Depth of 85■■) The ingot poured and cast had shrinkage cavities inside the riser frame, but no shrinkage cavities occurred inside the mold.

On the other hand, ingots cast at the same temperature using only a mold had shrinkage cavities inside the mold.

[Effects of the Invention] As explained above, by the production method of the present invention, it is possible to produce a TiAl-based intermetallic compound alloy that is free from problems during melting such as bumping, base metal adhesion, and shelf hanging, and has less oxygen contamination. I can do it.

Further, it is possible to obtain an ingot in which no shrinkage holes (shrinkage cavities) remain in the main body.

[Brief explanation of drawings]

FIG. 1 is a chart showing the oxygen analysis value of a TlAl ingot melted in a calcia crucible, and FIG. 2 is a chart showing the relationship between temperature ε and hydrogen solubility of AI.

Claims (2)

[Claims] (1) Titanium 48-70 atomic%, aluminum 30-5
A raw material consisting of 2 atom% is melted in a calcia crucible, and Ti
When melting an Al-based intermetallic compound alloy, it is recommended to first heat the titanium raw material in vacuum and degas it, then charge the titanium and aluminum raw materials into the crucible and melt them using the vacuum induction melting method. A method for producing a TiAl-based intermetallic compound alloy. (2) When pouring the molten TiAl-based intermetallic compound alloy according to claim (1) into a mold made of metal such as cast iron or copper, a calcia riser frame is used to delay the solidification of the top of the ingot. A method for forming a TiAl-based intermetallic compound alloy, characterized by preventing the generation of shrinkage cavities (shrinkage pores) in the main body of the lump.